Calculate molecular masses of H₂ , O₂ and Cl₂ .

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3. ATOMS AND MOLECULES

easy

Calculate the molecular masses of $H_2$, $O_2$ and $Cl_2$.

A

$9\,u$, $36\,u$ and $84\,u$

B

$6\,u$, $18\,u$ and $36\,u$

C

$ 2\,u$, $32\,u$ and $71\,u$

D

$12\,u$, $36\,u$ and $84\,u$

Solution

$(i)$ Molecular mass of $H_2$ (hydrogen)

$=$ Atomic mass of hydrogen $\times 2$

$= 1 \times 2 = 2\,u$

$(ii)$ Molecular mass of $O_2$ (oxygen)

$=$ Atomic mass of oxygen $\times 2$

$= 16 \times 2 = 32\,u$

$(iii)$ Molecular mass of $Cl_2$ (chlorine)

$=$ Atomic mass of chlorine $\times 2$

$= 35.5 \times 2 = 71\,u$

Standard 9

Science

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