Question

(1) MgNis commonly used in school laboratory to generate a small amount of ammonia gas (NH) by adding water to it Mg3Nz(s) +_ H2O(l) + NH3(g) +_ Mg(OH)(s) Fill in the 3 blanks in the above equation to balance it, i.e., making the no. of each type of element atoms are the same on both sides. You don't need to write "1" if you think it is the answer for a blank. . The recipe of a fake gold: (2) Calculate the density and profit of the fake gold on p. 16 of Chap01. (You may use computer to do the calculations and put down the answers below.) Ans: Metal d Gold (Au) Iridium Osmium Os) Ruthenium (Ru) Iron (Fe) Nickel (NI) Copper Cul Rhodium (Rh) g/cm) 19.28 4 22. 6 22. 12.37 7.88 8.90 9.93 12.41 Mass % 5 1 2 0.8 1 8.7 7.82 0.87 0.32 0.25 0.24 US Sig 49.96 28.23 13.41 2.92 0.0049 0.018 0.0081 37.93 (3) What is the density of the urine shown on p.38 of Chap01? You may write down a range for the answer, but it should be as accurate as possible. (This question actually tests your ability in figuring out the values in the scale.) Ans. Sunlight (4) The diagram shown on the right illustrates how rainbow is created when white light hits a water droplet Circle the region(s) at which refraction occurs. AirDroplet Air (5) (a) Galinstan is an alloy of 3 metals (in full name): , and (b) Galinstan has an advantage over mercury. What is this advantage which makes people suggest replacing mercury by Galinstan in glass-thermometer? Ans: Question 3: The "urine" in the question refers to that in the photo shown below.

Answer 1

MgzNg(s) + H2O(l) — 5. NH3(9) Mg(OH) (3) For the Both side atom to be same Balanced reaction will be- 13. Mg, Na(9) + 6 Hoold) Now checking it o 2NH (9) + 3 mg (6H), (S) n Right side ; left side mg w do ben bog 1929= H 12 12 o So the reaction is balanced.