Question no. 1.11) What is the concentration of sugar (C12h22O11) in mol/l if its 20g are dissolved in enough water to make a final volume up to 2 litres.
Solution – Given, mass of sugar = 20gm
Volume of solution = 2 l
So, molarity (concentration) of sol. = (given mass of solute (sugar)/molar mass of sugar) x volume of solution.
= (20/342)x2=0.11 mole/litre
Question no.1.22) If the speed of light is 3×10^8 m/s,calculate the distance covered by light in 2.00 nano-seconds.
Solution-Given, speed=3×10^8, distance=?, time=2 ns
Since, distance=speedxtime
Therefore, 2x3x10^8 = 6×10^8 metres
Question no. 1.2) Calculate the mass percent of different elements present in Na2SO4.
Solution-Total mass of Na2SO4=2×23+32+4×16=142
Mass% of Na=(Mass of Na/Mass of Na2SO4)x100=(46/142)x100 =32.39 %
Mass% of S=(Mass of S/Mass of Na2SO4) x 100=(32/142)x100=22.53%
Mass% of O=(Mass of O/Mass of Na2SO4) X 100=(64/142)X100=45.07%
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