200 grams of a soil is taken and dried completely in bright sunshine. The mass of dried soil is found to be 170 grams. Calculate the percentage of water (or moisture) present in the given sample of the soil.

0.5 gm of fuming H_(2)SO_(4) (Oleum) is diluted with water. This solution is completely neutralised by 26.7 ml of 0.4 M NaOH solution. Calculate the percentage of free SO_(3) in the given sample. Give your answer excluding the decimal places.

Hydocarbons, obtained from coal and coal tar and from oil and gas wells, are organic compounds composed entirely of C and H. A 0.1647 g sample of a pure hydrocarbon was burned in a C - H combustion train to produce 0.4931 g of CO_(2) and 0.2691 g of H_(2)O . Determine the masses of C and H in the sample and the percentages of these elem ents in the hydrocarbon. Strategy: Step 1 . Use the observed mass of CO_(2) to determine the mass of C in the original sample using the information that there is 1 mol of C atoms in each mole of CO_(2) . Step 2 . Use the observed mass of H_(2)O to calculate the mass of H in the original sample using the fact that there are 2 mol of H atoms in each mole of H_(2)O . (We can also calculate the mass of H by subtracting the mass of C from the mass of sample. However, it is good experimental practice, when possible, to base both on experimental measurements as this would help to check for errors in the anlysis of calculation.) step 3 . Calculate the percentages by mass of each element in turn, using the relationship % Element = ("Gram of element")/("Gram of sample") xx 100 %

12. g of an impure sample of arsenious oxide was dissolved in water containing 7.5 g of sodium bicarbonate and the resulting solution was diluted to 250 mL . 25 mL of this solution was completely oxidised by 22.4 mL of a solution of iodine. 25 mL of this iodine solution reacted with same volume of a solution containing 24.8 g of sodium thiosulphate (Na_(2)S_(2)O_(3).5H_(2)O) in one litre. Calculate teh percentage of arsenious oxide in the sample ( Atomic mass of As=57 )

(i) A cubical metal block of side 10cm is floating in a vessel contatining mercury. The vesel has a square cross section of side length 15cm. Water is poured into the vessel so that the metal block just gets submerged. Calculate the mass of water that was poured into the vessel. It is given that relative density of the metal and mercury are 7.3 and 13.6 respectively. (ii) In the last question, in place of water if we poured another liquid of relative density 'r' it was found that when the metal block ws just completely submerged it was no longer touching mercury. what is value of r?

Calculates the masses of cane sugar and water required to prepare 250 grams of 25% cane sugar solution-