Question

take a close look at the combination reactions (also called synthesis reactions) below to figure out what they have in common

2na(s) + cl₂(g) → 2nacl(s)

2h₂(g) + o₂(g) → 2h₂o(g)

2co(g) + o₂(g) → 2co₂(g)

whats common to the reactions above?
select the best answer.

two or more reactants have combined to form a more complex product, a new compound.

two compounds combine to form two new compounds.

one compound breaks down into two new compounds.

in each reaction, an element reacts with a compound and takes the place of another element in that compound.

Explanation:

In the first reaction, \(2Na(s)+Cl_{2}(g)\to2NaCl(s)\), two reactants (sodium \(Na\) and chlorine \(Cl_{2}\)) combine to form a more complex product \(NaCl\). In the second reaction, \(2H_{2}(g)+O_{2}(g)\to2H_{2}O(g)\), two reactants (\(H_{2}\) and \(O_{2}\)) combine to form \(H_{2}O\). In the third reaction, \(2CO(g)+O_{2}(g)\to2CO_{2}(g)\), two reactants (\(CO\) and \(O_{2}\)) combine to form \(CO_{2}\).

A synthesis reaction (combination reaction) is a type of reaction where two or more reactants combine to form a single product. The second option “Two compounds combine to form two new compounds” is incorrect as in the given reactions, the number of products is one. The third option “One compound breaks down into two new compounds” is a decomposition reaction, which is the opposite of what is shown. The fourth option “In each reaction, an element reacts with a compound and takes the place of another element in that compound” is a single - replacement reaction, which is not the case here.

Answer:

Two or more reactants have combined to form a more complex product, a new compound.