WBJEE Tutors in Howrah

density of water = 1g/ml

mass of 18ml of water = densityx volume =( 1g/ml)*(18ml) = 18g

no. of mol of water = 18g/18g/mol = 1 mol

1molecule of water contain 8 electrons

1mol of water contain 8*(6.02x1023)

= 48.16x1023

Ans. 6.023x10^23 atoms of Hydrogen weigh 1.008 g.

So, 1 atom of Hydrogen weighs 1.008/(6.023x10^23) g = 0.167x10^(-23) g = 1.67x10^(-27) kg .

answer is -2

36 g of water

The equivalent mass of a substance is the ratio of molecular mass to the number of electrons gained (or lost) or change in the oxidation state. That  is equivalent mass = molecular mass/number of electrons gained or lost or

= molecular mass/change in oxidation state

Here, potassium permanganate changes to potassium manganate. The relevant chemical reaction is:

Only 1 electron is gained by permanganate ion to convert to manganate ion. We can also see that the oxidation state of manganese is +7 in permanaganate ion and it changes to +6 in manganate ion. That is, the oxidation state changes by 1.

Thus, the equivalent mass = molecular mass/1 = molecular mass = M

Hence, the equivalent mass of KMnO4 is M when it converts over to K2MnO4. 

so answer is A

Velocity of Ambulance = \(90 \times \frac {5}{18} = 25 m/s\)

Velocity of Police Van = \(80 \times \frac {5}{18} = 22.2 m/s\)

f (observed frequency) = (\(1 + \frac {\Delta V}{C}\)) x \(f_0\) (Original frequency)

∴ Police Van which follows ambulance
    \(∴  \Delta v = (22.2 - 25) m/s = - 2.8m/s \\         f = (1 - \frac {2.8}{340}) \times 250 \\ = 0.9918 \times 250\\ = 247.94 Hz\)

Police Van approaches towards ambulance

∴ \(f = (1 + \frac {2.8}{340}) \times 250 \\ = 1.00823 \times 250 \\ = 252.0589 Hz\)

Gelatin or gelatine is a translucent, colorless, brittle (when dry), flavorless food derived from collagen obtained from various animal raw materials. It is commonly used as a gelling agent in food, pharmaceutical drugs, photography, and cosmetic manufacturing .It is added in ice-creams to prevent it smoothness and fine texture as it acts as a protective colloid.

Oxidation state of NItrogen in n2h4 is -2.  2(-2) + 4(+1)= 0

therefore two N makes it -4 , since they lose 10 e-  , hence total charge is +6, and since H is still +1 ,  Two N divides the +6 .

then ox state of N is +3 in the new compound Y.

so answer is D.

 3BaCl2 + 2Na3PO4  ------------->  Ba3(PO4)2 + 6Nacl

                  0.5 mol           0.20 mol               x mol           

                First find which is the limiting reagent?

              0.5/3 = 1/6          0.2/2 = 1/10

                            1/10 < 1/6

              thus,  Na3PO4 is the limiting reagent.

               Now, 1/10 = x/1

                             x = 0.1 mol.

(d) may be the ansr.

7:32 is the ratio of their no of molecules.