Question

plz help....?!????? ​

Answer 1

${\Large{\bf{Given}}}\begin{cases}\longrightarrow Given \:weight\: of \:HNO_{3}=54g\\ \longrightarrow Volume \:of \:water =450ml \end{cases}$

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So, Molecular weight of $HNO_{3}$ = 1+14+16×3=15+48=63gm.

Now,

No. of moles =$\dfrac{Given\:Weight}{Molecular\:weight}$

$\implies n =\dfrac{54g}{63g}$

$\implies n =\dfrac{\cancel{54g}^{6}}{\cancel{63g}^{7}}$

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${\underline{\boxed{\red{.\degree. n =\dfrac{6}{7}}}}}$

Now, volume is 450 ml = $\dfrac{450L}{1000}$

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So,

$\Large\orange{\boxed{\purple{M=\dfrac{n}{V(in \:L)}}}}$

where,

M is molarity of solution.

$\implies M =\dfrac{6}{7\times \dfrac{450}{1000}}$

$\implies M =\dfrac{6\times 1000}{7\times 450}$

$\implies M =\dfrac{\cancel{6}^{2}\times 100\cancel{0}}{7\times \cancel{45\cancel{0}}^{15}}$

$\implies M =\dfrac{200}{105}$

${\underline{\boxed{\purple{.\degree. M =1.90}}}}$

Answer 2

$\huge{\underline{\underline{\boxed{\sf{\purple{Answer ࿐}}}}}}$

750 ml of 0.5 M HCl have 0.375 moles.

250 ml of 2 M HCl have 0.5 moles.

Total moles =0.875moles

Total volume =750+250=1000ml=1L

Molarity =

Volume

Moles

=

1

0.875

=0.875M

Hence, the correct option is D.