Question

Chloral hydrate, $C_2{H}_{3}C{l}_3{O}_3$, is a drug formerly used as a sedative and hypnotic. A sample of chloral hydrate contains $30\times {10}^{18}$ atoms of carbon. How many atoms of hydrogen does this sample contain?

• A. $15\times {10}^{18}$
• B. $30\times {10}^{18}$
• C. $45\times {10}^{18}$
• D. $60\times {10}^{18}$
• E. $90\times {10}^{18}$

Answer 1

The correct option is C $45\times {10}^{18}$

The molecular formula of chloral hydrate is $C_2{H}_{3}C{l}_3{O}_2$. One molecule of chloral hydrate contains 2 C atoms and 3 H atoms.
A sample of chloral hydrate contains $30\times {10}^{18}$ atoms of carbon. The number of atoms of hydrogen present in this sample $=30\times {10}^{18}\times \frac{3}{2}=45\times {10}^{18}$.