Question

Number of atoms in 4.25 g of NH3 is
approximately


(A) 6 × 10²³ (B) 15 × 10²³

(C) 1.5 × 10²³ (D) 2.5 × 10²³​

Answer 1

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$\implies$$\large\bf{\underline{\red{VERIFIED✔}}}$

$Moles \: of  \: NH3 = \frac{4.25}{17}\\ =0.236 moles \\ ∴ Number of molecules  \\ = \: 0.236×6.022×1023 molecules \\ 1 molecule of NH3 contains 4 atoms \\ ∴ Number of \: atoms \\ =4×0.236×6.022×1 {0}^{23} \\ ≈6×1 {0}^{23}  atoms$

So, Option A) is the Correct Answer.

$\boxed{I \:Hope\: it's \:Helpful}$

Answer 2

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(A) 6×10 ^23

QUESTION

Number of atoms in 4.25 g of NH3 is

approximately

OPTIONS

(A) 6 × 10²³

(B) 15 × 10²³

(C) 1.5 × 10²³

(D) 2.5 × 10²³

FORMULA USED

$number \: of \: molcules \: in \: given \: eight=\frac{given \: weight}{molecular \: mass} \times 1 \: mole$

$1 \: mole = 6.023 × {10}^{23} \: or \: 6 \times {10}^{23}$

WE KNOW

N stands for atomic symbol of nitrogen

H stands for atomic symbol of hydrogen

atomic mass of nitrogen (N) is 14

atomic mass of hydrogen (H) is 1

SOLUTION

step 1

calculate the molecular mass of NH3

NH3= N+H+H+H

= N +3H

molecular mass = atomic mass of nitrogen + 3 x atomic mass of hydrogen

.

so molecular mass of NH3 is 17 u

step 2

calculate the number of molecules in given weight

$\frac{given \: weight}{molecular \: mass} \times 1mole \\ = \frac{4.25}{17} \times 6 \times {10}^{23} \\ \frac{0.25}{1} \times 6 \times {10}^{23} \\ 0.25 \times 6 \times {10}^{23}$

step 3

calculate number of atoms

$number \: of \: atoms =no \: of \: molecules \: \times number \: of \: toms \: in \: one \: molecule \\ 0.25 \times 6 \times {10}^{23} \times 4 \\ 4 \times 0.25 \times 6 \times {10}^{23} \\ 1.00 \times 6 \times {10}^{23} \\ 6 \times {10}^{23}$

HOPE IT HELPS