Answer: B) 10 - 12 Explanation: Scientists estimate the volume of blood in a human body to be approximately 7 percent of body weight. An average adult body with a weight of 150 to 180 pounds will contain approximately 4.7 to 5.5 liters of blood. An average child with a body weight of 80 pounds will have approximately half the amount of blood as an adult. The amount of blood in a human body varies, depending on factors such as age, sex, overall health and even where a person lives. For example, men tend to have more blood than women of comparable size and weight. Interestingly, people who live at high altitudes may have up to two liters of extra blood compared to those who live at lower altitudes. Because the air at higher altitudes has less oxygen, people who live at high altitudes need extra blood to deliver the right amount of oxygen to their lungs.   We know that 1 Pint = 0.473 liters   Hence, an average amount of blood in the human body = 4.7 - 5.5 lit = 10 - 12 pints.

Answer: C) capillary action phenomenon Explanation: The absorption of ink by blotting paper involves capillary action phenomenon because the blotting paper is a thin and a smooth paper which allows a little thicker liquids like ink to absorb.

Answer: D) 36 yrs Explanation: Let present ages of Sumit=w, Krishna=x, Rishabh=y and Rohit=z , thenw+x+y = 43x3 = 129 ---(i) andw+y+z = 49x3 = 147 ---(ii)Subtracting (i) from (ii), (w+y+z) - (w+x+y)=147 -129 , z- x =18 ---(iii)Given Rohit's age => z = 54, so from (iii), x = 54-18 = 36