Payload is defined as the difference between the mass of the displaced air and the mass of the balloon. Calculate the payload when a balloon of radius 10 m, mass 100 kg is filled with helium at 1.66 bar at 27°C. (Density of air = 1.2 kgm-3 and R = 0.083 bar dm3 K-1 mol-1)

The wavelength of first line of lyman series in hydrogen tom is 1216 angstrom. the wavelength of first line of lyman series for 10 times ionsied sodium atom will be

Find the Gold Number if 700 ml of standard gold solution is just prevented from coagulation by adding 0.35 g of starch before adding 1 ml of 10% NaCl solution?

We know that Gold number is the minimum amount of protective (lyophilic) colloid in milligrams which prevents the  coagulation or flocculation of 10 ml of standard hydro gold sol by the addition of 1 ml of 10% NaCl solution. 

The concept of gold number was given by Zsigmondy.

As par Questions 700 ml of gold solution requires (0.35gm ) or 350 mg of starch.

Hence the amount of lyophilic colloid in mg to protect 10 ml of gold solution is  starch $=(\frac{350\times \mathrm{10)÷}}{700}=\mathrm{5\; mg}$

$\mathrm{"Gold\; number\; is\; 5"}$

The number of moles of KMnO 4​ reduced by one mole of KI in alkaline medium is:

Answer key : 2

An oxide, X2​O3​ is oxidized to XO4^−​ by Cr 2​ O 7^2−​ in acid medium. The number of moles of X2​O3​ oxidized per mole of Cr2​O7^2−​ is

Answer key: 3/4