The observed geometry of SF 6, as shown in Figure 7.2, is highly symmetric: all bond lengths are identical and all bond angles are 90o. The F atoms form an octahedron about the central S atom: four of the F atoms form a square with the S atom at the center, and the other two F atoms are above and below the S atom.Comments (0)Video Transcript. Give the geometry and approximate bond angles around the central atom in CCl3-. (LO 8.1) (a) Trigonal planar, 120° (b) Trigonal pyramidal, …Q. Assertion :Bond angle of P F 3 >P Cl3 but bond angle of P Cl3 <P Br3 Reason: The bond angles show an increase on decreasing electronegativity of attached other atom on central atom but in P F 3 pπ−dπ bonding results in an increase in bond angle. Q. arrange in the increasing order of bond angle : 1)SF6 , CCl4, H2O , NH3. 2)AlCl3 , H2S , BeH2 ,H2OThis problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: What is the theoretical bond angle in NF3? A. = 102 ∘∘ B. < 109.5 ∘∘ C. = 109.5 ∘∘ D. > 109.5 ∘∘ E. = 120 ∘∘. What is the theoretical bond angle in NF 3? Here’s the best way to solve it.Apr 25, 2016 · All four compounds would ideally want a set of $90^\circ$ angles which nitrogen cannot achieve due to steric stress; instead, the angles are expanded to $102^\circ$ ($\ce{NF3}$) and $107^\circ$ ($\ce{NH3}$). This seems couner-intuitive, because the smaller atoms require a larger bond angle. Research on the effects of parenting on how kids turn out shows that while parents can influence their kids, they can't really change them, and the main area a parent really can im...Solution for Compare BF3 and NF3 • Bond Angle: [Select] • Hybridization: [Select] Polarity: [Select] [Select] F-B-F angle is Smaller Both have the same Bond… Skip to main content. close. Start your trial now! First week only $4.99! arrow_forward. Literature guides Concept explainers Writing guide Popular textbooks Popular high school textbooks Popular Q&A …Jul 16, 2020 · $\ce{NF3}$ had smaller bond angle as electrons were nearer to the more electronegative fluorine atom, thereby reducing bond pair - bond pair repulsion (of N-F bonds) and thus allowing contraction of bond angle. Further, in $\ce{NCl3}$ bond angle was larger than both $\ce{NH3}$ and $\ce{NF3}$ due to steric Nitrogen trichloride is a planar molecule. The nitrogen atom is directly bonded with three chlorine atoms on the same plane. According to the VSEPR theory, it has a bond angle of 120 degrees.The molecular geometry or shape of H 2 S is bent, angular or V-shaped. The ideal electron pair geometry of H 2 S is tetrahedral. H 2 S does not possess any hybridization as per Drago’s rule. The H 2 S molecule possesses a mutual bond angle of 92.1° between the bonded atoms.In trigonal planar molecular geometry, there is an F-B-F bond angle which has 120 degrees angles. It also includes three fluorine atoms; the BF3 molecule exhibits a trigonal planar geometric shape. At the BF3 molecular geometry, there are three B-F bonds. These bonds maintain the planar-T-like structure after joining the three fluorine atoms in ... Dec 29, 2016 · As you would know, adjacent electron bond pairs repel, and it's this repulsion that gives ammonia an H-N-H bond angle of 107°. Now fluorine, with an electronegativity of 3.98, does an even better job of pulling the N-F electron bond pairs towards it. Therefore, tetrahedrals have a bond angle of 109.5 degrees. How scientists got that number was through experiments, but we don't need to know too much detail because that is not described in the textbook or lecture. Using the example above, we would add that H 2 O has a bond angle of 109.5° and CO 2 would have a bond angle of 180°.Q 3. Among the following species, the isostructural pairs are N F 3, N O3−, BF 3, H 3O+, H N 3. View Solution. Q 4. BF 3 and N F 3 both molecules are covalent, but BF 3 is non-polar and N F 3 is polar. Its reason is. View Solution. Q 5. The correct increasing bond angle among BF 3, P F 3 and CI F 3 follows the order. The drop in bond angles from hydrogen to fluorine is sufficiently explained by the much longer bond lengths of the $\ce{OF2}/\ce{NF3}$ species when compared to the corresponding hydrogen species due to fluorine using p-orbitals for bonding where hydrogen uses its 1s orbital.Chemistry questions and answers. Look at your structure geometry in Data Table 2 for ammonia (NH3) and nitrogen trifluoride (NF3). Although models cannot show this simply, the actual F-N-F bond angles in NF3 are around 102o whereas the H-N-H bond angles in ammonia are around 107o. According to what you know about the VSEPR theory, why …The Insider Trading Activity of Bond Darryl on Markets Insider. Indices Commodities Currencies StocksCorrect option is C. H 3 T e + < H 3 S e + < H 3 S + < H 3 O +Correct order of bond angle :N H 3 < P H 3 < A s H 3 < S b H 3O F 2 < O H 2 < O C l 2H 3 T e + < H 3 S e + < H 3 S + < H 3 O +B F 3 = B C l 3 = B B r 3 = B I 3. Was this answer helpful? Which one of the following represents the correct increasing order of bond angles in given molecules?The bond angle is more in \[P{F_3}\] due to the lone pair-bond pair repulsion. As the fluorine is smaller in size and more electronegative than the hydrogen atom; the bond pair of electrons shifts partially towards the fluorine atom. Note: There are many factors on which the bond angle depends: 1.Hybridization: The bond angle is …Q 3. Among the following species, the isostructural pairs are N F 3, N O3−, BF 3, H 3O+, H N 3. View Solution. Q 4. BF 3 and N F 3 both molecules are covalent, but BF 3 is non-polar and N F 3 is polar. Its reason is. View Solution. Q 5. The correct increasing bond angle among BF 3, P F 3 and CI F 3 follows the order. The NF3 bond angle is 102degree. There is more distortion than for NH3 because the single bonds are taking up less room, close to the nitrogen. Fluorine is more electronegative than hydrogen and the electron density in the N-F bond is skewed towards the fluorine. The PF3 bond angle will be about 109degree since it has a trigonal pyramidal ...May 14, 2022 · NF3 lewis structure angle. As shown in the above figure, the bond angle is about 102.5 o in NF 3 as the molecular geometry is trigonal pyramidal and has a lone pair due to which the standard tetrahedral angle of 109 o has deviated and decreased to 102.5 o. Research on the effects of parenting on how kids turn out shows that while parents can influence their kids, they can't really change them, and the main area a parent really can im...4 Sept 2021 ... Bond angle Trick in Chemical bonding | IIT JEE ... VSEPR Theory||Difference in bond angle of NH3 and NF3,H2O and H2S||part 5||Professor Aziz Atif.If you own a savings bond you may name beneficiaries to the bond if, just as you can name beneficiaries for any other asset. Naming a beneficiary means that the bond can go to some...Explain why the bond angle in a water molecule is smaller than 109.5 degrees. Predict the bond angles in the following molecules. (a) NF3 (b) SO2Cl2 (c) CBr4 (d) F2CO (e) PH3 (f) HOCl; Predict the bond angles in each of the following molecules: Predict the bond angles of the following molecules. a. XeO4 b. NF3 c. SCl2Click here:point_up_2:to get an answer to your question :writing_hand:c dr3 al3 1113the correct decreasing order of nearest bond anglea cif pf3Because the lone pair of electrons occupies more space than the bonding pairs, we expect a decrease in the Cl–Sn–Cl bond angle due to increased LP–BP repulsions. D With two nuclei around the central atom and one lone pair of electrons, the molecular geometry of SnCl 2 is bent, like SO 2, but with a Cl–Sn–Cl bond angle of 95°. The ... Chemistry: Principles and Practice. Chemistry. ISBN: 9780534420123. Author: Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer. Publisher: Cengage Learning. SEE MORE TEXTBOOKS. Solution for 20 The F-N-F bond angle in the NF3 molecule is slightly less than A) 60° B) 109.5° C) 180° D) 90° E) 120°.Creating a 3-D character online for free involves selecting a 3-D character generator and selecting from the myriad options presented for each characteristic of the avatar's appear...Dec 30, 2013 · Answer link. There are three basic steps to determining the bond angles in a molecule: > 1. Write the Lewis dot structure for the molecule. Assume that you must determine the bond angles in "BF"_3. "B" is less electronegative than "F", so "B" becomes the central atom. If we have three "F" atoms, that means that we are going to use all three ... This is Ammonia (NH3), and really what we want to know is why does NH3 have a bond angle of 107 degrees? We'd expect it with four things bonded to that centr...Mar 15, 2018 · The difference in bond angles in $\ce{NF3}$ and $\ce{NH3}$ is only determined by the electronegativity difference between the central atom and the bonded atom. As $\ce{F}$ is more electronegative than $\ce{H}$, in $\ce{NH3}$, bonding electron pair shifts more towards $\ce{N}$ than they shift in $\ce{NF3}$. So, the bond angle increases. For tax purposes, it is in the best interest of companies to ensure amortization of the bonds they issue are accounted for, especially when they issue them at a discount. Companies...The correct order of bond angles in OCl2, H 2O and F 2 would be. View Solution. 3. View Solution. 4. bond angle is largest in OF2 , H2O , OCl2 , OBr2 write them in increasing order of bond angle? View Solution. 5. Asending order of …kimiaUNY. Apr 18, 2015. Angle Bond. In summary, NH3 and N (CH3)3 both have trigonal pyramidal molecular structures, but N (CH3)3 has a slightly larger bond angle of approximately 110 degrees compared to NH3's bond angle of approximately 107 degrees. This difference is caused by the presence of three methyl groups in N (CH3)3, which …Although models cannot show this simply, for molecules like NF3 (whose structure you drew earlier), the actual bond angles may not exactly equal the angles predicted by VSEPR theory. For example, the F-N-F bond angles in NF3 are less than the 109.5° tetrahedral angle. Why do you think this might be so?The drop in bond angles from hydrogen to fluorine is sufficiently explained by the much longer bond lengths of the $\ce{OF2}/\ce{NF3}$ species when compared to the corresponding hydrogen species due to fluorine using p-orbitals for bonding where hydrogen uses its 1s orbital.In trigonal planar molecular geometry, there is an F-B-F bond angle which has 120 degrees angles. It also includes three fluorine atoms; the BF3 molecule exhibits a trigonal planar geometric shape. At the BF3 molecular geometry, there are three B-F bonds. These bonds maintain the planar-T-like structure after joining the three fluorine atoms in ... Given, ClF3 , NF3 , BF3 . We have to draw the Lewis structure of given molecules and rank them from sma …. Draw Lewis structures for each molecule. - chlorine trifluoride, CIF3 - nitrogen trifluoride, NF3 - boron trifluoride, BF3 Rank the molecules from smallest bond angle between nearest neighbors to largest bond angle between nearest neighbors.PH 3,AsH 3,SbH 3,NH 3 in order of increasing polarity. Two substances X and Y are dissolved in water under suitable conditions. X is a gas while Y is a solid under normal conditions. Solution of Y is found to conduct electricity but not X. Based on the conclusion, identify the nature of bond present in X and Y with appropriate reasons as given ...Oct 24, 2010 · What is the purpose of increasing F-A-F bond angles in OF2, NF3, CF4, BeF3, and BeF2? The purpose of increasing F-A-F bond angles is to reduce the …The general green angle behind upgrading a computer is easy enough to understand. Learn more about the most important thing to know before upgrading your desktop computer. Advertis...Oct 24, 2010 · Oct 24, 2010. Angles Bond Increasing. In summary, the conversation discusses arranging the AFn species (BeF3, BeF2, CF4, NF3, and OF2) in order of increasing F-A-F bond angles. The suggested order is OF2, NF3, CF4, BeF3, and BeF2. The conversation also mentions the importance of considering the effect of lone pairs on bond angles, which can ... However, we predict a deviation in bond angles because of the presence of the two lone pairs of electrons. 4. The three nuclei in BrF 3 determine its molecular structure, which is described as T shaped. This is essentially a trigonal bipyramid that is missing two equatorial vertices. The F axial –Br–F axial angle is 172°, less than 180° because of LP–BP …This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. See Answer. Question: Predict the bond angles in the following molecules. (a) NF3 ° (b) SO2Cl2 ° (c) CBr4 ° (d) F2CO ° (e) PH3 ° (f) Predict the bond angles in the following molecules. (a) NF 3.Aug 22, 2019 · One thing that would lessen the molecular $\ce{NF3}$ dipole moment is a smaller $\ce{NF}$ bond angle (compared to $\ce{NH}$), which increases the lateral component of the dipole at the expense of the axial, making the (axial) resultant smaller. I think fluorine is larger than hydrogen and maybe this would tend to push the fluorine atoms out ... The greater electronegativity of the chlorine atoms causes the bond pairs to be more localized and increases the repulsion between them, decreasing the bond angle. Conclusion: Therefore, the overall order of bond angles in gaseous NF 3, SbF 3, and SbCl 3 is NF3 > SbCl3 > SbF3, with the bond angles decreasing as the electronegativity of …12 Sept 2023 ... Although geometries of NH3 and H2O molecules are distorted tetrahedral, The bond angle in water is less than that of ammonia .Corporate bonds are investment securities that are issued by public and private corporations. Learn what corporate bonds are and how you can invest in them. Calculators Helpful Gui...In trigonal planar molecular geometry, there is an F-B-F bond angle which has 120 degrees angles. It also includes three fluorine atoms; the BF3 molecule exhibits a trigonal planar geometric shape. At the BF3 molecular geometry, there are three B-F bonds. These bonds maintain the planar-T-like structure after joining the three fluorine atoms in ...NH3 Bond angles. There are three single bonds and one lone pair of electrons in the NH3 molecule. It has a molecular geometry of trigonal pyramidal which also looks like a distorted tetrahedral structure. The shape is distorted because of the lone pairs of electrons. This pair exerts repulsive forces on the bonding pairs of electrons. Hier sollte eine Beschreibung angezeigt werden, diese Seite lässt dies jedoch nicht zu.Q 1. In which of the following molecules bond angle is the largest? View Solution. Q 2. Which bond angle θwould result in the maximum dipole moment for the triatomic molecule YXY. View Solution. Q 3. Which of the following accounts for the bond angle of 104.5o in water molecules? View Solution.May 24, 2020 · Bond angle of NF 3 (102 degree) is lesser than in NH3 (107) as per VSEPR theory which suggests that in case of less electronegative terminal atoms like H, Bond …Bond angles mainly depend on the following three factors: Hybridization: Bond angle depends on the state of hybridization of the central atom. Hybridization: s p X 3, Bond angle: 109 ∘, Example: C H X 4. Hybridization: s p X 2, Bond angle: 120 ∘, Example: B C l X 3. Hybridization: s p, Bond angle: 180 ∘, Example: B e C l X 2.Nitrogen trichloride is a planar molecule. The nitrogen atom is directly bonded with three chlorine atoms on the same plane. According to the VSEPR theory, it has a bond angle of 120 degrees.Q 3. Among the following species, the isostructural pairs are N F 3, N O3−, BF 3, H 3O+, H N 3. View Solution. Q 4. BF 3 and N F 3 both molecules are covalent, but BF 3 is non-polar and N F 3 is polar. Its reason is. View Solution. Q 5. The correct increasing bond angle among BF 3, P F 3 and CI F 3 follows the order. Arrange the following species in increasing order of bond angle: NF3, NCl3, NBr3, NI3. See answers. Advertisement. kunaljj. Because of greater electonegativity there is a shift of electrons towards the atom reducing the bond pair - bond pair repulsion and inturn reducing the bond angle. so the decreasing order of electonegativity is. F, Cl, Br, I.Photo-blending effects can turn two average pictures into a single piece of art. By adjusting the transparency of two images, you can bring out the dominant attributes of both phot...The bond angle of PH3 is less than that of PF3. Both PH3 and PF3 are pyramidal in shape. Both have one lone pair on phosphorous. But PF3 has partial double bond character due to back π-donation of electrons from p orbitals of F atom to empty d orbitals of P. This results in large repulsion between P-F bonds and hence bond angle is large.This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. See Answer. Question: Predict the bond angles in the following molecules. (a) NF3 ° (b) SO2Cl2 ° (c) CBr4 ° (d) F2CO ° (e) PH3 ° (f) Predict the bond angles in the following molecules. (a) NF 3.Solution. The correct option is D All of the above are correct. a) H2O has lone pair-lone pair repulsions whereas N H3 has only one lone pair and hence, the bond angle in ammonia is greater than water. b) Due to the greater electronegativity difference, the bond pairs are more close to the nitrogen in the case of ammonia and hence has the ... I mean, how often do you get to do hot yoga for free? Working out in the heat can be miserable—which is why you already know to do outdoor exercise in the early morning or late eve...The actual measured bond angle of NF3 is 102.50 In VSEPR theory (Valence shell electron pair theory) the number of electron pairs around the nitrogen are counted and there are four. If all of ...18 Jan 2020 ... Out of `H_(2)O` which one has higher bond angle and why ... The dipole moment of NH3 is greater than NF3. Why? / chemical ...For tax purposes, it is in the best interest of companies to ensure amortization of the bonds they issue are accounted for, especially when they issue them at a discount. Companies...This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. See Answer. Question: Predict the bond angles in the following molecules. (a) NF3 ° (b) SO2Cl2 ° (c) CBr4 ° (d) F2CO ° (e) PH3 ° (f) Predict the bond angles in the following molecules. (a) NF 3.In P F 3, P is sp3 - hybridized but the bond angle is little less that 109∘.28 (but far greater tha n 90∘) due to bond pair - lone pair repulsion. In CI F 3, Cl is sp3 d hybridized. It has T - shape and hence the bond angle is around 90∘. Therefore the correct order of increasing bond angle is CI F 3 < P F 3 <BF 3. Suggest Corrections.NF3 lewis structure angle. As shown in the above figure, the bond angle is about 102.5 o in NF 3 as the molecular geometry is trigonal pyramidal and has a lone pair due to which the standard tetrahedral angle of 109 o has deviated and decreased to 102.5 o.. NF3 uses. Nitrogen trifluoride is primarily used for manufacturing microelectronics …CF_4. Determine the bond angle of BCl_3. Determine the electron geometry, molecular geometry, and idealized bond angles for each of the following molecules. A) CF4 B) NF3 C) OF2 D) H2S. Predict the molecular structure and the bond angles for the compound PCl5. Determine the molecular shape and bond angles of C2H4.As a result the bond angle decreases to 102.4°, whereas in N H 3 it decreased to 107.3° only. P H 3 and P F 3 are also pyramidal in shape with one lone pair on P. But P F 3 has great bond angle than P H 3. This is due to resonance in P F 3, leading to partial double bond character as shown in figure 2. As a result the repulsion between P −F ... The actual measured bond angle of NF3 is 102.50 In VSEPR theory (Valence shell electron pair theory) the number of electron pairs around the nitrogen are counted and there are four. If all of ...Research on the effects of parenting on how kids turn out shows that while parents can influence their kids, they can't really change them, and the main area a parent really can im...Question: 4. Draw Lewis structures for BF3 and NF3. Compare the geometries bond angles, and polarities. Give the electron pair geometry and the molecular geometry of BF3 and NF3 according to VSEPR.5. Draw the three resonance structures of the CO, molecule. There are 3 steps to solve this one.
Q 1. In which of the following molecules bond angle is the largest? View Solution. Q 2. Which bond angle θwould result in the maximum dipole moment for the triatomic molecule YXY. View Solution. Q 3. Which of the following accounts for the bond angle of 104.5o in water molecules? View Solution.. Towne marine
Oct 11, 2023 · Learn how to draw the lewis dot structure of NF3, a colorless gas with a smell of moldy and a molecular geometry of a trigonal pyramid. Find out the bond angle, polarity, electrons, and hybridization of NF3 using VSEPR rules and examples. Nitrogen trichloride is a planar molecule. The nitrogen atom is directly bonded with three chlorine atoms on the same plane. According to the VSEPR theory, it has a bond angle of 120 degrees.Follow this rule: 1)Bond angle is directly proportional to size of surrounding atom and inversely proportional to the size of central atom. Therefore, correct order is: SbF3 < SbCl3 < NF3. Likes ( 0) Reply ( 4) what about nbepr. Like (0) each central atom has one lone pair of electrons. So can't be decided using that.Q 3. Among the following species, the isostructural pairs are N F 3, N O3−, BF 3, H 3O+, H N 3. View Solution. Q 4. BF 3 and N F 3 both molecules are covalent, but BF 3 is non-polar and N F 3 is polar. Its reason is. View Solution. Q 5. The correct increasing bond angle among BF 3, P F 3 and CI F 3 follows the order. View Solution. 2. The correct order of increasing bond angles in the following triatomic species is (a) NO2+. View Solution. 2 2, and O. View Solution. Q 5. View Solution. Click here:point_up_2:to get an answer to your question :writing_hand:the correct order of bond angle of no2 no2 and no2 is.Nitrogen trichloride is a planar molecule. The nitrogen atom is directly bonded with three chlorine atoms on the same plane. According to the VSEPR theory, it has a bond angle of 120 degrees.Research on the effects of parenting on how kids turn out shows that while parents can influence their kids, they can't really change them, and the main area a parent really can im...Predict the molecular structure (including bond angles) for each of the following. a. PCl_3 b. SCl_2 c. SiF_4 d. Which of the molecules above have net dipole moments (are polar)? Determine whether the molecule CH_2CHCH_3 is polar: A) The molecule is polar only because there are slightly polar bonds. B) The molecule is polar because there are ...The Insider Trading Activity of Bond Jonathan on Markets Insider. Indices Commodities Currencies Stocks6 Dec 2013 ... Comments14 ; VSEPR Theory - Basic Introduction · 1.4M views ; NF3 Molecular Geometry / Shape and Bond Angles · 85K views ; CO2 Molecular Geometry and&n...arrange in the increasing order of bond angle : 1)SF6 , CCl4, H2O , NH3. 2)AlCl3 , H2S , BeH2 ,H2O Dec 15, 2019 · Explanation: → In NF 3, the central atom is nitrogen, which is more electronegative than antimony in SbF 3 and SbCl 3. The greater electronegativity of …The H - N - H bond angle in N H 3 is greater than F - N - F bond angle in N F 3. View Solution. Q 5. Out of NH3 and NF3 which has more reactivity? Give reasons using diagram of bond moments. View Solution. Click here:point_up_2:to get an answer to your question :writing_hand:which has the largest bond angle. CH2F2 Bond Angles. The Hydrogen and Fluorine atoms repel each other in accordance with the VSEPR theory, giving the CH2F2 molecule a tetrahedral shape with bond angles of 109.5°. CH2F2 Molecular Geometry. Molecular geometry is one of the properties that can be ascertained by taking a glance at the Lewis structure obtained. It can be noted that ...This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: Arrange in order from the smallest to the largest bond angle: CH3+, NF3, NH4+. Group of answer choices CH3+, NF3, NH4+ NF3, CH3+, NH4+ NF3, NH4+, CH3+ NH4+, NF3, CH3+. Arrange in order from the smallest to the ... Question. Consider the molecules CH 4,N H 3 and H 2O. Which of the given statements is false? A. The H−C−H bond angles in CH4, the H−N −H bond angle in N H3, and the H−O−H bond angle in H2O are all greater than 90∘. B. The H−O−H bond angle in H2O is larger than the H−C−H bond angle in CH4. C.The given question has five different compound words. The objective is to find the ideal bond angle ... Hours Predict the ideal bond angles for each of the following compound using the molecular shape determined by the VSEPR theory +) NF3 b) CC14 c)SO3 d) NH4 e) SF6 OE) a) 120° b) 109.5°C) 120.0ºd) 109.5° e) 90.0 OA) a) 109.5° b) < 109.5 ...Arrange the following molecules in order of increasing bond angles around the central atom: BeF2, BF3, CH4, NH3, H2O. H2O< NH3 < CH4 < BF3 < BeF2. Mention the shape of NH3 and H2O. Predict the shapes of the given covalent molecules on the basis of VSEPR theory: AlCl3, PH3, CCl4. What is the expected geometry of AB5 molecule?Mar 23, 2023 · Chemical formula NF3 The molecular geometries of the NF3 Trigonal pyramid The electron geometries of NF3 Tetrahedral Hybridization Sp3 Bond angle …Alex, Natasha and Mary Ann talk about Finix's Stripes, blue skies and paparazzi all in the realm of a busier-than-usual tech cycles. Hello, and welcome back to Equity, a podcast ab....