Q8. Exhaled air and atmosphere is quite different. As our body use up oxygen for respiration, there is less oxygen in exhaled air compared to atmosphere. In the atmosphere, there would be about 21% of oxygen, but in exhaled air, there is about 16% of oxygen. So C.
Q15. The question states that the pure substance has a melting point of 110. Impure substance breaks the lattice structure and decreases the melting point. Hence, the most impure substance will have the lowest melting point range. So A.
Q21. When group 1 metal is added to cold water, it floats on water and hydrogen gas is made. Out of these 4 options, lithium is the only group 1 metal. So B.
I don't think so, I think you should only know that there is more carbon dioxide and water vapour in expired air compared to inhaled air.
Thank you. Do I need to know any other % in expired air though?
Hi, thank you for your question.
Q8. Exhaled air and atmosphere is quite different. As our body use up oxygen for respiration, there is less oxygen in exhaled air compared to atmosphere. In the atmosphere, there would be about 21% of oxygen, but in exhaled air, there is about 16% of oxygen. So C.
Q15. The question states that the pure substance has a melting point of 110. Impure substance breaks the lattice structure and decreases the melting point. Hence, the most impure substance will have the lowest melting point range. So A.
Q21. When group 1 metal is added to cold water, it floats on water and hydrogen gas is made. Out of these 4 options, lithium is the only group 1 metal. So B.