law of chemical combination

Four samples of water [H_(2)O] are collected from different sources, Each sample on analysis was found to containsame percentage of oxygen. Which law of chemical combination is demonstrated by the above observation?

If 100 grams of calcium carbonate (whether in the form of marble or chalk) are decomposed completely, then 56 grams of calcium oxide and 44 grams of carbon dioxide are obtained'. Which law of chemical combination is illustrated by this statement ?

Carbon combines with hydrogen to forom three compounds A, B and C . The percentage of hydrogen in A, B and C .is 25, 14.3, and 7.7, respectively. (a) Find the empirical formula of the compounds. (b) Which law of chemical combination does this example illustrate? How?

Two substances X and Y are colourless gases and are formed by the combination of sulphur and oxygen. Substance X is obtained by the combination of 6.0 g of sulphur of 6.0 g of sulphur with 6.0 g of oxygen. Substance Y is formed when 8.6 g of sulphur and 12.9 of oxygen combine. (a) What is the mass ratio of the elements in the two substances ? (b) Which law of chemical combination does it support ? (c) Give the statement of the law.

When 5g of calcium is burnt in 2g of oxygen, then 7 g of calcium oxide of produced. What mass of calcium oxide will be produced when 5g of calcium is burnt in 20 g of oxygen ? Which law of chemical combination will govern your answer ?

The following data are obtained when dinitrogen and dioxygen react together to form different compounds : {:(,"(i)","(ii)","(iii)","(iv)"),("Mass of dinitrogen ",14,14,28,28),("Mass of dioxygen ",16,32,32,80):} Which law of chemical combination is obeyed by the above experimental data ? Give its statement.

When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combination will govern your answer?

Calcium carbonate decomposes, on heating , to form calcium oxide and carbon dioxide. When 10 g of calcium carbonate is decomposed completely, then 5.6 g of calcium of oxide is formed. Calculate the mass of carbon dioxide formed. Which law of chemical combination will you use in solving this problem ?

A student collected three samples of water from different sources and found out the percentage of hydrogen and oxygen by mass in thse samples. It should have been 1 : 8 by mass. But it was different in all three samples, Moreover, the values did not match (i) In your opinion why did the student get different results for different samples ? (ii) What should have been done by him ? (iii) Which law of chemical combination is supported by these observations (iv) How will you check the purity of water in the laboratory ?