Answer the following questions only in 'one sentence each :
What is a 'syndrome ' ?

Answer the following questions only in 'one sentence each : What is protobiogenesis ?

Answer the following questions in one sentence each : Name isotopes of hydrogen.

Answer the following questions only in 'one sentence each : Name the type of T-lymphocyte which secretes perforins ?

Answer the following questions only in 'one sentence each : (i) Mention the frist vaccine developed against any human diseases.

Answer the following question in one sentence What is battery?

Answer the following questions in one sentence each : The atomic mass number of an element is 18, and the element contains 8 electrons. What is the number of protons and neutrons in it ?

Answer the following question on one sentence : What is specific gravity ?