Chemistry - Study Mode
[#416] Which among the following elements is found in maximum percentage in the human body ?
Correct Answer
(D) Oxygen
Explanation
Solution: Oxygen is found in maximum percentage in the human body.
[#417] Iodine can be separated from a mixture of Iodine and Potassium Chloride by
Correct Answer
(C) Sublimation
Explanation
Solution: Iodine is well known to sublime (change from solid to gas without becoming liquid inbetween) when heated. However sodium chloride has a melting point much higher than that of iodine. Therefore, a mixture of iodine and sodium chloride can be separated by using a sublimation apparatus, with solid iodine collected by condensation on a cold surface.
[#418] The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing is:
Correct Answer
(D) Helium
Explanation
Solution: Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used in deep commercial diving. The helium is included as a substitute for some of the nitrogen, to reduce the narcotic effect of the breathing gas at depth. It helps to reduce nitrogen narcosis and to avoid the dangers of oxygen toxicity. With a mixture of three gases, it is possible to create mixes suitable for different depths or purposes by adjusting the proportions of each gas.
[#419] Which one among the following is not a mixture?
Correct Answer
(A) Graphite
Explanation
Solution: Graphite is not a mixture. This is because graphite is a pure element which cannot split into its constituent particles.
[#420] The gas used to dilute oxygen for breathing by deep sea divers is:
Correct Answer
(D) Helium
Explanation
Solution: Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used in deep commercial diving. The helium is included as a substitute for some of the nitrogen, to reduce the narcotic effect of the breathing gas at depth. It helps to reduce nitrogen narcosis and to avoid the dangers of oxygen toxicity. With a mixture of three gases, it is possible to create mixes suitable for different depths or purposes by adjusting the proportions of each gas.