What is obtained by the dehydrohalogenation of allyl chloride?

Reaction of but$-2-$ene with acidic $KMnO_4$ gives:

When neopentyl alcohol is heated with an acid,it slowly converts into an $85:15$ mixture of alkenes $A$ and $B$,respectively. What are these alkenes $?$ (Note: $A$ is the major product and $B$ is the minor product.)

Which of the following compounds on ozonolysis gives a product that gives a silver mirror with Tollen's reagent?

The addition of $HBr$ is easiest with

In the reaction $CH_3CH=CH_2 + H_2O + [O]$ $\xrightarrow{KMnO_4/Acid} CH_3-CH(OH)-CH_2(OH)$ $\xrightarrow{[O]} X + HCOOH$,what is $X$?