Class 12th

KCl solution has molality (m) = 3.3, [Means 3.3 mol of KCl dissolved in 1 kg of solved]

Total mass of solution = mass of solute + mass of solvent

= 3.3 * 74.5 + 1000 gm

= 1245.85 gm

Volume of solution = $\frac{Mass}{density}=\frac{1245.85}{1.2}=1038.20ml$

$M=\frac{moles*1000}{V\left(ml\right)}=\frac{3.3*1000}{1038.2}=3.17M$          

Ans. = 3 (the nearest integer)

If Rate = $K{\left[NO\right]}^a{\left[H_2\right]}^b$  

Case I => $7*10^{-9}=K{\left(8*10^{-5}\right)}^a{\left(8*10^{-5}\right)}^b$

Case II =>   $2.1*10^{-8}=k{\left(24*10^{-5}\right)}^a{\left(8*10^{-5}\right)}^b$

Therefore, $\frac{7\text{?}*10^{-1}}{2.1}={\left(\frac{1}{3}\right)}^a$

or ${\left(\frac{1}{3}\right)}^1={\left(\frac{1}{3}\right)}^a\therefore a=1$           

Ans. = 1

New expenditure of C7

= 1.4*365253

= 511354.2

Expenditure of Nigeria = 798294

Nigeria > C7

Expenditure of France= 1210988

France > Austria,

Molecular formula of Mohr' salt, FeSO₄. (NH₄)₂SO₄.6H₂O.

Molecular formula of potash alum = K₂SO₄.Al₂ (SO₄)₃.24H₂O. Overall molecular formula of potash alum = KAl (SO₄)₂. 12H₂O. Ratio of water molecules in Mohr' salt and Potash alum

$=\frac{6}{12}=\frac{1}{2}=0.5=5*10^{-1}$       

Ans. = 5

The difference between the growth rate of UK & France during 2020 – 21 was (28.4 – 5.1) = 23.3% while Vietnam's exports growth rate is 23.4%.

All the solution have higher ion production with respect to 0.1 M C₂H₅OH i.e. 0.1 M Ba₃ (PO₄)₂, 0.1 M Na₂SO₄, 0.1 M KCl and 0.1 M Li₃PO₄. Hence all have lowered freezing point than 0.1 M C₂H₅OH (which is non-ionisable in aqueous medium).

Ans. = 4

From statement (I), the table, we can observe that Myanmar has the highest annual growth

$\Rightarrow \frac{\left(\frac{4938-3408}{3408}*100\right)}{1}=44.89\mathrm{\%}$

Statement (II), in interval 2019-20, Egyptn has second the highest growth rate, while Nigeria have the highest growth.

Statement (III), Nigeria register third the highest growth is wrong because it exhibits 28.2% which is the highest in 2017 to 2018.

Statement (IV),

Growth rate of 2016-2017

$=\left(\frac{194904-207171}{207171}\right)*100=-5.9\mathrm{\%}$

Growth rate of 2017-2018

$=\left(\frac{68108-64968}{64968}\right)*100=4.8\mathrm{\%}$

Difference = 4.8 – (–5.9) = 10.7%

Average annual growth

Nigeria $=\frac{\left(\frac{9300?3387}{3387}*100\right)}{6}=29.09\mathrm{\%}$

UK $=\frac{\left(\frac{2285862?584793}{584793}*100\right)}{6}=48.48\mathrm{\%}$

Egypt $=\frac{\left(\frac{285288?107001}{107001}*100\right)}{6}=27.77\mathrm{\%}$

Portugal $=\frac{\left(\frac{94875?34620}{34620}*100\right)}{6}=29\mathrm{\%}$

Portugal experienced third the highest growth.

In electro-refining, impure metal (blister copper) is used as an anode while precious metal like Au, Pt gets deposited as anode mud.

$2sin\frac{\pi }{8}sin\frac{2\pi }{8}tan\frac{3\pi }{8}sin\left(\pi -\frac{5\pi }{8}\right)sin\left(\pi -\frac{6\pi }{8}\right)sin\left(\pi -\frac{7\pi }{8}\right)$

$={\left(\frac{1}{\sqrt[]{2}}\right)}^2.2si{n}^2\frac{\pi }{8}si{n}^2\frac{3\pi }{8}$

^{$=\frac{1}{4}.{\left(2sin\frac{\pi }{8}sin\frac{3\pi }{8}\right)}^2$}

$=\frac{1}{4}.{\left(2sin\frac{\pi }{8}sin\frac{3\pi }{8}\right)}^2$