What is the difference b/w synthesis reaction and combination reaction​

Direct Combination Reaction : The reaction in which two or more substances combine to form a single substance is called direct combination reaction. Synthesis Reaction: The reaction in which two or more elements combine to form a compound is called direct combination reaction.

HOPED I HELP BRIANEST PLZZ

if you mean hydrogen and oxygen then water is the product

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.