Mass of : (a) 0.2 mole of oxygen atoms ? (b) 0.5 mole of water molecules ?

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3. ATOMS AND MOLECULES

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What is the mass of :

$(a)$ $0.2$ mole of oxygen atoms ?

$(b)$ $0.5$ mole of water molecules ?

A

$4.2 \,g$ and $10.0\, g$

B

$3.2 \,g$ and $ 9.0\, g$

C

$6.3 \,g$ and $ 9.0\, g$

D

$5.5 \,g$ and $10.0\, g$

Solution

$(a)$ Mass of $1$ mole $O-$ atoms $=$ $16\, g$

Mass of $0.2$ mole $O-$ atoms $= 16 \times 0.2 = 3.2 \,g$

$(b)$ Mass of $1$ mole of $H_2O$ molecules $= 18\, g$

Mass of $0.5$ mole of $H_2O$ molecules $= 18 \times 0.5 = 9.0\, g$

Standard 9

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