It’s called an isotope which is an atom with the same number of protons but a different number of neutrons
B is the answer I think better sure
Sodium chloride and prussic acid are formed
NaCN+HCl→NaCl+HCN
The answer here is D - bases tend to feel slippery. This is because they tend to dissolve oils on your skin, reducing the friction between your fingers or hands when you rub them together.