Answer:
a. cis-4-methylcyclohexanol and sodium chloride
Step-by-step explanation:
An SN2 reaction is a concerted mechanism of nucleophilic substitution of an alkyl halide in which there is inversion of configuration of the product.
This inversion of configuration occurs because the entering group attacks the substrate from the backside. In the transition state, both the leaving group and entering group are partially bonded to the substrate in the front and backsides respectively.
Hence, if we start with trans-1-chloro-4-methylcyclohexane, we end up with a product of inverted configuration which is cis-4-methylcyclohexanol and sodium chloride as a byproduct.