Question

Two elements always combine together in a fixed ratio by weight.

• A. True
• B. False

Answer 1

The correct option is B False

The statement, "Two elements always combine in a fixed ratio by weight." is false. In a compound, their ratio of masses can remain fixed. But two elements can combine in different ratios to form different compounds.
For example, consider C and O. They combine to form $CO$ and $C{O}_2$.
12 g of C combine with 16 g of O to form $CO$. The ratio by weight of C to O is $12:16$ or $3:4$.
12 g of C combine with 32 g of O to form $C{O}_2$. The ratio by weight of C to O is $12:32$ or $3:8$.
Thus, elements can combine in different ratios to form different compounds but the ratio remains fixed for a particular compound.