I got some multiple choice questions to practice and I'm not sure of how to get the answers...

1). Which of the following corresponds to the COC bond angle in dimethyl ether?-94 degrees, 110degrees, 180 degrees, 122 degrees, or 60 (i think it's 110
2). classify the reaction below as oxidation, a reduction, or neither.
PhCO2H -->PhCH2OH
3). among the compounds water, but-1-yne, but-2-yne, and ethane, which are stronger acides than ammonia
a). water and but-1-yne b). water and ethane c). but-1-yne and ethane d). but-1-yne and but-2-yne
4). which of the following alcohols undergoes dehydration upon heating with concentrated H2SO4 without carbocation rearrangement?
a). 2-methyl-2phenylpropan-1-ol b). 2-methylhexan-3-ol c). 3-methylpentan-3-ol d). 3,3-dimethylpentain-2-ol e). both a and b
5). which of the following alkyl halides can produce only a single alkene product from when treated with sodium methoxide?
a). 2-chloro-3-ethylpentane
b). 2-chloro-2-methylpentane
c). 2-chloro-4-methylpentane
d). 3-chloro-2-methylpentane
e). 3-chloro-3-ethylpentane
6). which of the following is not a property of ehters which makes them good solvents in organic reactions?
a). they dissolve a wide range of polar substances
b).they dissolve " " of np substances
c).they are nonhydroxylic
d).they have relatively high boiling pts for their molecular weights
e).they are normally unreactive toward strong bases

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I just wanted to get these checked. I think 1 is b, 2 is a, 3 is d, 4 is c, 5 is e and 6 is a

1) To determine the COC bond angle in dimethyl ether, you need to consider the geometry of the molecule. Dimethyl ether, CH3OCH3, has a tetrahedral geometry around the oxygen atom. The bond angle you are looking for is the angle between the two C-O bonds. In a tetrahedron, all bond angles are approximately 109.5 degrees. Therefore, the closest answer choice is 110 degrees.

2) To classify the reaction PhCO2H --> PhCH2OH as oxidation, reduction, or neither, you need to compare the oxidation states of the carbon atoms. In PhCO2H (benzoic acid), the carbon in the carboxyl group has an oxidation state of +3, while the carbon in PhCH2OH (benzyl alcohol) has an oxidation state of +1. Since the oxidation state of carbon decreases from +3 to +1, this reaction is a reduction.

3) To determine which compounds are stronger acids than ammonia among water, but-1-yne, but-2-yne, and ethane, you need to consider the stability of the conjugate base for each compound. The strength of an acid is determined by the stability of its conjugate base. Ammonia (NH3) is a weak base, and its conjugate base, NH2-, is stabilized by electron-donating substituents. Among the given compounds, water and but-1-yne have electron-withdrawing substituents (i.e., oxygen and a triple bond, respectively), which stabilize their conjugate bases more effectively than NH3 does. Therefore, the correct answer is (a) water and but-1-yne.

4) To determine which alcohol undergoes dehydration upon heating with concentrated H2SO4 without carbocation rearrangement, you need to consider the stability of the carbocation formed during the dehydration process. In this case, the carbocation stability is influenced by the type of substituents attached to the carbocation carbon. Secondary and tertiary carbocations are more stable than primary carbocations, as they have more alkyl groups donating electron density. Among the given options, only 3-methylpentan-3-ol (option c) can form a secondary carbocation upon dehydration, which is relatively stable and undergoes dehydration without rearrangement.

5) To determine which alkyl halide can produce only a single alkene product when treated with sodium methoxide, you need to consider the regioselectivity of the elimination reaction. In this case, the regioselectivity is influenced by the stability of the resulting alkene. The more substituted the alkene, the more stable it is. Among the given options, 2-chloro-4-methylpentane (option c) can only form a single alkene product (2-methylpent-1-ene) because the resulting alkene is the most stable due to the presence of a methyl group on the double bond.

6) To determine which property of ethers does not make them good solvents in organic reactions, you need to consider the properties that contribute to their solvent capabilities. Ethers are known for being good solvents due to their ability to dissolve a wide range of polar substances, dissolve nonpolar substances, have nonhydroxylic characteristics, have high boiling points for their molecular weights, and being unreactive toward strong bases. Among these properties, option c (they are nonhydroxylic) is not a property that makes ethers good solvents. Hydroxyl (-OH) groups, which ethers do not have, contribute to the hydrophilic nature of solvents like alcohols and water.