The quantity of Nitrogen, Oxygen and Carbon dioxide in the air is 75.6%, 23.04% and 1.36%, Let's work out the quantity of each in 25 liters of air.

The ratio of hydrogen and oxygen in water is 2 : 1 Let's work out the percentage of hydrogen and oxygen in water.

The fundamental frequency of an air-filled open organ pipe is 500 Hz. The frequecny of the first harmonic in a carbon dioxide-filled organ pipe, closed at one end, is equal to the frequency of the first harmonic in the first pipe. Find the lengths of each of the organ pipes . The velocities of sound in air and carbon dioxide are 300 m*s^(-1) and 264 m*s^(-1) , respectively .

A compound of carbon, hydrogen and oxygen contains 40% of carbon and 6.67% of hydrogen. Vapour density of the compound is 2.813 times of the vapour density of oxygen. Determine the empirical formula and molecular formula of the compound.

Let's write by calculating %:- Rs. 2.25 out of Rs. 5.

The income of Amina Bibi was increased by 20% and later decreased by 20%. Let's work out the total change of percentage of her income.

The length of a rectangle is increased by 15% and the breadth is reduced by 15%. Let’s work out in percentage the increase or decrease of area.

If 64 water - filled buckets of equal volume are taken out from a cubical water - filled tank, then 1/3 th of water remains in the tank. If the length of one edge of the tank is 1*6 metres, then calculate the quantity of water that can be hold in each bucket ?

Let's get 15% of discount if the bill of electricity is paid in time. My aunt got a rebate of Rs. 54 paying the bell in time. Let's work out the total amount of the bill.

A polystyrene, having the formula Br_3C_6H_3(C_2H_6)_n was prepared by heating styrene with tribromobenzoic peroxide in the absence of air. If it was found to contain 10.46% bromine by weight, Find the value of n.