HSC Science (General) १२ वीं कक्षा - Maharashtra State Board Question Bank Solutions for Physics

Answer in brief:

Show that rms velocity of an oxygen molecule is `sqrt2` times that of a sulfur dioxide molecule at S.T.P.

At what temperature will oxygen molecules have same rms speed as helium molecules at S.T.P.? (Molecular masses of oxygen and helium are 32 and 4 respectively).

Answer in brief:

Compare the rms speed of hydrogen molecules at 127°C with rms speed of oxygen molecules at 27ºC given that molecular masses of hydrogen and oxygen are 2 and 32 respectively.

Choose the correct option:

The graph shows variation of displacement of a particle performing S.H.M. with time t. Which of the following statements is correct from the graph?

Answer in brief:

State the characteristics of stationary waves.

An electron, a proton, an α-particle, and a hydrogen atom are moving with the same kinetic energy. The associated de Broglie wavelength will be longest for ______.

State the importance of Davisson and Germer experiment.

What is the speed of a proton having de Broglie wavelength of 0.08 Å?

Answer in brief.

State the postulates of Bohr’s atomic model.

Derive the expression for the energy of an electron in the atom.

In an ideal gas, the molecules possess ______.

If the density of oxygen is 1.44 kg/m³ at a pressure of 10⁵ N/m², find the root mean square velocity of oxygen molecules.

When a gas is heated, its temperature increases. Explain this phenomenon on the basis of the kinetic theory of gases.

Explain, on the basis of the kinetic theory of gases, how the pressure of a gas changes if its volume is reduced at a constant temperature.

Calculate the ratio of the mean square speeds of molecules of a gas at 30 K and 120 K.

Two vessels A and B are filled with the same gas where the volume, temperature, and pressure in vessel A is twice the volume, temperature, and pressure in vessel B. Calculate the ratio of the number of molecules of the gas in vessel A to that in vessel B.

Find the kinetic energy of 5 litres of a gas at STP, given the standard pressure is 1.013 × 10⁵ N/m².

Calculate the average molecular kinetic energy 

1. per kmol 
2. per kg 
3. per molecule 

of oxygen at 127°C, given that the molecular weight of oxygen is 32, R is 8.31 J mol⁻¹K⁻¹ and Avogadro’s number N_A is 6.02 × 10²³ molecules mol⁻¹.

Energy is emitted from a hole in an electric furnace at the rate of 20 W when the temperature of the furnace is 727°C. What is the area of the hole? (Take Stefan’s constant σ to be 5.7 × 10^-8 Js^-1 m^-2K^-4.)

The emissive power of a sphere of area 0.02 m² is 0.5 kcal s^-1m^-2. What is the amount of heat radiated by the spherical surface in 20 seconds?