Questions

We know that, elements in the same group of the periodic table have similar characteristics. Here magnesium and strontium are the same 2nd group elements and have same behavior. 

Therefore, strontium behaves same as magnesium. 

In the above options, sperms are the haploid cells. In humans, haploid cells are those have only half the number of usual number of chromosomes. Sperm, gamates and egg cells are the haploid cells examples.

Allows for expansion or contraction of the trachea. Hence, so large masses of food can pass through the esophagus during swallowing.

Most organic compounds contain carbon and hydrogen.

The process which involves absorption of heat is endothermic.

Here given all the options are involving in absorption of heat. Hence, all the above are endithermic.