1. A solution is prepared by addition of 10 g salt in 100 g water. To make the concentration of the solution 15% (w/w), the amount of salt added to the solution is approximately (1) 5.8 g (2) 5.0 g (3) 6.9 g (4) 7.6 g 2. Which of the following colloids does not have the same dispersion medium as that in the remaining three? (1) Milk of Magnesia (2) Mud (3) Butter (4) Milk 3. A gas jar contains 10 g of oxygen gas. In which condition, the interparticle space between oxygen molecules would decrease? (1) Removal of 5 g gas from gas jar (2) Decreasing pressure (3) Addition of more oxygen gas to the same gas jar (4) Transferring gas to another gas jar having double volume 4. Which of the following is not an element? (1) Diamond (2) Brass (3) Mercury (4) Sulphur