Science (English Medium) Class 11 - CBSE Question Bank Solutions

An ideal gas is kept in a long cylindrical vessel fitted with a frictionless piston of cross-sectional area 10 cm² and weight 1 kg in figure. The vessel itself is kept in a big chamber containing air at atmospheric pressure 100 kPa. The length of the gas column is 20 cm. If the chamber is now completely evacuated by an exhaust pump, what will be the length of the gas column? Assume the temperature to remain constant throughout the process.

The weather report reads, "Temperature 20°C : Relative humidity 100%". What is the dew point?

The condition of air in a closed room is described as follows. Temperature = 25°C, relative humidity = 60%, pressure = 104 kPa. If all the water vapour is removed from the room without changing the temperature, what will be the new pressure? The saturation vapour pressure at 25°C − 3.2 kPa.

The temperature and the dew point in an open room are 20°C and 10°C. If the room temperature drops to 15°C, what will be the new dew point?

Figure shows two rigid vessels A and B, each of volume 200 cm³, containing an ideal gas (C_v = 12.5 J K⁻¹ mol⁻¹). The vessels are connected to a manometer tube containing mercury. The pressure in both the vessels is 75 cm of mercury and the temperature is 300 K. (a) Find the number of moles of the gas in each vessel. (b) 5.0 J of heat is supplied to the gas in vessel A and 10 J to the gas in vessel B. Assuming there's no appreciable transfer of heat from A to B, calculate the difference in the heights of mercury in the two sides of the manometer. Gas constant, R = 8.3 J K⁻¹ mol⁻¹.

Using figure, find the boiling point of methyl alcohol at 1 atm (760 mm of mercury) and at 0.5 atm.

A glass contains some water at room temperature 20°C. Refrigerated water is added to it slowly. when the temperature of the glass reaches 10°C, small droplets condense on the outer surface. Calculate the relative humidity in the room. The boiling point of water at a pressure of 17.5 mm of mercury is 20°C and at 8.9 mm of mercury it is 10°C.

An adiabatic cylindrical tube of cross-sectional area 1 cm² is closed at one end and fitted with a piston at the other end. The tube contains 0.03 g of an ideal gas. At 1 atm pressure and at the temperature of the surrounding, the length of the gas column is 40 cm. The piston is suddenly pulled out to double the length of the column. The pressure of the gas falls to 0.355 atm. Find the speed of sound in the gas at atmospheric temperature.

Find the elastic potential energy stored in each spring shown in figure when the block is in equilibrium. Also find the time period of vertical oscillation of the block.

For any arbitrary motion in space, state whether the following statement is true:

`"V"_"average"` = `(1/2)("v"("t"_1) + "v"("t"_2))`

For any arbitrary motion in space, state whether the following statement is true:

`"V"_"average"` = [r(t₂) - r(t₁) ] /(t₂ – t₁)

For any arbitrary motion in space, state whether the following statement is true:

v (t) = v (0) + a t

(The ‘average’ stands for average of the quantity over the time interval t₁ to t₂)

For any arbitrary motion in space, state whether the following statement is true:

`"r"("t") = "r"(0) + "v"(0)"t"  + 1/2  "a"  "t"^2 `

(The ‘average’ stands for average of the quantity over the time interval t₁ to t₂)

The number of significant figures in 0.06900 is ______.

The sum of the numbers 436.32, 227.2 and 0.301 in appropriate significant figures is ______.

The mass and volume of a body are 4.237 g and 2.5 cm³, respectively. The density of the material of the body in correct significant figures is ______.

The numbers 2.745 and 2.735 on rounding off to 3 significant figures will give ______.

The length and breadth of a rectangular sheet are 16.2 cm and 10.1cm, respectively. The area of the sheet in appropriate significant figures and error is ______.

Why do we have different units for the same physical quantity?

Calculate the length of the arc of a circle of radius 31.0 cm which subtends an angle of `pi/6` at the centre.