| • | SA Part A |
| • | SA Part B |
| • | SB/SX |
| • | SA, SB, SX |
| • | SA Part B |
Here's my attempt at answering KVPY Question Paper of Stream SB/SX conducted on October 31, 2010. The answers may or may not be right. Verify the logic on your own.
PART-I (Answer any three sections. One mark for right answers, -0.25 for wrong answers)
MATHEMATICS
PHYSICS
CHEMISTRY
BIOLOGY
PART-II (Answer any two sections. Two marks for right answers, -0.5 for wrong answers)
MATHEMATICS
PHYSICS
CHEMISTRY
110 A solution containing 8.0 g of nicotine in 92 g of water freezes 0.925 degrees below the normal freezing point of water. If the molal freezing point depression constant Kf = 1.85°C mol-1 then the molar mass of nicotine is
A. 16
B. 80
C. 320
D. 160
The depression is half the freezing point depression constant. So, there must be 0.5 moles. Now the unit given in the question seems to be wrong. The unit for molal freezing point depression must be °C kg mol-1. So, keeping that in mind, the molality of the solution is 0.5 mole per kg. That is, in 100g, there is 0.05 moles which is 8 g. 16 g in 0.1 moles and 160 g for 1 mole.
BIOLOGY
111: A host cell has intracellular bacterial symbionts. If the growth rate of the bacterial symbiont is always 10% higher than that of the host cell, after 10 generations of the host cell the density of bacteria in host cells will increase
A. by 10%
B. two-fold
C. ten-fold
D. hundred-fold
This is intracellular symbiont. Imagine there is one symbiont in one cell. So, when that host cell becomes 10, the total number of symbionts becomes 11, that is 1.1 per cell. (in one generation) Similarly when it becomes 100 in the next generation, the symbionts become 121. (1.2 per cell) Going on, in the 10th generation, it'll reach around 2.5 per cell which I rounded as two-fold.
112 In a diploid organism, there are three different alleles for a particular gene. Of these three alleles one is recessive and the other two alleles exhibit co-dominance. how many phenotypes are possible with this set of alleles?
A. 3
B. 6
C. 4
D. 2
This is nothing other than how the blood groups are. There is three different alleles, A, B and i. i is recessive, A and B exhibit co-dominance. And we have: AB, A, B and O phenotypes
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