Class 12th

$m=\frac{w*1000}{molecularwt*w_{solvent}}=\frac{10.2*1000}{176*150}$  

$=\frac{1020\cancel{0}}{176*15\cancel{0}}=0.386$  

  $\Delta T_f=K_f*m$

3.9 * 0.386

$\therefore x*10^{-1}=15.05*10^{-1}$  

Ans = 15

B.C.C structure

a = 300 pm = 300 * 10^-12 m

d = 6g/cm³

z = 2

$d=\frac{Z*M}{a^3}$

$6=\frac{2*A}{{\left(300*10^{-10}\right)}^3}=\frac{2*A}{27*10^{-24}}$  

$\therefore AtomsofM$ = 3.69 * 6.022 * 10²³

= 22.22 * 10²³

the nearest integer = 22

Sphalarite             ZnS

Calamine              ZnCO₃

Galena                  PbS

Siderite                FeCO₃

$T_{90\mathrm{\%}}=\frac{2.303}{k}log\frac{100}{10}$

$T_{50\mathrm{\%}}=\frac{2.303}{k}log\frac{100}{50}$

$\frac{T_{90\mathrm{\%}}}{T_{50\mathrm{\%}}}=\frac{log10}{log2}=\frac{1}{0.301}=3.32$

$A\to 286$

$Z=81$

Statement I is true as atoms are electrically neutral because they contain equal number of positive and negative charges.

Statement II is wrong as atom of most of the elements are stable and emit characteristic spectrum. But this statement is not true for every atom.

Let the capacity of container be 70L (LCM of 5,7 & 10)

Now,

I container, milk = 28L

    Water = 42L

II container, milk = 20L

    Water = 50L

III container, milk = 21L

    Water = 49L

In large container, milk = (28 + 20 + 21)

= 69L

Water = 42 + 50 + 49

= 141L

Milk : Water = 23 : 47

Path $bc$  is an isochoric process.

$\therefore$ Work done by gas along path $bc$ is zero.

Distance is same. So, speed will be inversely propornonel to time.

Ratio of time taken by car and motorcycle = 28 : 20

= 7 : 5

So, ratio of speed of car and motorcycle = 5 : 7

5/7 = 32/M

M = (32*7)/5 = 44.8 km/hr

Work done by 10 men = work done by 16 women

Work done by 15 men = work done by (16*3/2) women

=24 women

So, 40 women and 15 men = 40 women and 24 women

= 64 women

Therefore we can say

16 women will take 40 days

Hence, 64 women will take 40/4 =10 days