English one word substitutions for all competetive exams

When a mutation is limited to the substitution of one nucleotide pair of DNA, it is called as

Which one is a nucleophilic substitution reaction among the following ?

Which one of the following pairs undergoes Snl substitution reaction faster and why?

Which one of the following pairs undergoes Snl substitution reaction faster and why?

Which one of the following reaction is an example of free radical substitution reaction?

In a group of 50 people, 35 speak Hindi, 25 speak both English and Hindi and all the people speak at least one of the two languages. How many people speak only English and not Hindi? How many people speak English?