Which of the following gases is poisonous?

The number of sigma $(σ)$ and pi $(π)$ bonds in pent$-2-$en$-4-$yne is

The major product of the following synthetic reactions is

The order of appearance of the following with rising temperature during the refining of crude oil is:

In which of the following reactions $1,3$-butadiene will be obtained as a major product?

Give distinguishing tests for the following:
$(a)$ Ethane and ethyne (Alkane and Alkyne $RC \equiv CH$)
$(b)$ Ethene and Ethyne (Alkene and Alkyne $RC \equiv CH$)
$(c)$ Dimethyl ethyne and ethyne
$(d)$ Ethane and Ethene (Alkane and alkene)