Question

a) Both A and R are true, and R is correct explanation of the assertion.
b) Both A and R are true, but R is not the correct explanation of the assertion.
c) A is true, but R is false.
d) A is false, but R is true.
15. Assertion: Colloidal mixture is quite stable.
Reason: Particles are too small to be seen by naked eyes and they do not settle down when left undisturbed.
16. Assertion: Nucleus plays an important role in cellular reproduction and cellular functions.
Reason: Nucleus contains chromosomes which are made up of DNA, which contains information for constructing and organising cells.
17. Assertion: A cricket fielder moves his hands down in the direction of the ball.
Reason: This is to reduce the force acting on his hands which can be explained by Newton’s second law of motion.
Q. No 18 - 20 contain five sub-parts each. You are expected to answer every part.
18. Read the table and answer the questions that follow:
Pragya tested the solubility of four different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution):
Substance dissolved Temperature in Kelvin (K) 283 293 313 333 353 Solubility Potassium nitrate 21 32 62 106 167 Sodium chloride 36 36 36 37 37 Potassium chloride 35 35 40 46 54 Ammonium chloride 24 37 41 55 66
a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 g of water at 313 K?
i) 62 g ii) 32 g iii) 31 g iv) 124 g
b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools?
i) Solid potassium chloride separates from the solution
2
ii) Volume of the solution increases​

Answer 1

A cell increases in volume if the external medium is hypotonic because a hypotonic solution has more concentration of solvent molecules than the fluid inside the cell. So, the solvent molecules move inside the cell from the region of higher concentration to the lower concentration by the process of endosmosis. The cell swells and increases in size.