CBSE Board Students Helpline

Q.1 :- Calculate the molarity of 25% by weight of aqueous solution of NaOH. Q.2 :- Calculate the molarity of 6g of CH3COOH solution of 600 m.l. volume. Q.3 :- How will you express the mass percentage of a component of solution? Q.4 :- What does it mean by 10% urea in water by mass? Q.5 :- What does it mean by volume percentage of solution? Q.6 :- What does it mean by 20% acetic aqueous solution? Q.7 :- If you are given with 10% by weight glucose solution. How will you calculate mole fraction of glucose in solution? Q.8 :- What is solubility? Q.9 :- On which factors does solubility depend? Q.10 :- What is the effect of pressure on solubility of gases in liquids? Q.11 :- What is the effect of temperature on solubility of gas in liquids? Q.12 :- How the solubility of a gas in liquids is an exothermic process? Q.13 :- Give an equation for relative lowering of vapour pressure? Q.14 :- Why the vapour pressure of solvent in solution is less than that of the pure solvent? Q.15 :- Derive the fo

Motion Question Bank Question 1. Calculate the average speed of a train, which covers 120 km in 2 hours. Distance covered by the train = 120 km Answer: Time taken = 2 h Question 2. How far does a car travel in 2.5 h if its average speed is 60 km/h ? Answer: Time taken by the car = 2.5 h Average speed = 60 km/h. Here we have to calculate the total distance covered by the car in 2.5h. Question 3. Convert 1 km/h to m/s. Answer: i.e., Question 4. A carriage moves 30 km in one hour. Calculate its speed in m/s. Is it average or uniform speed? Answer: The speed is average speed. Question 5. You are asked to run in a straight line. If you cover a distance of 5 m in each second, what is your (a) speed (b) velocity? Answer: speed = 5 m/s velocity = 5 m/s along the straight path. Question 6. Draw the velocity time graph of a body moving with uniform velocity of 5m/s. Answer: Question 7. Write the equation of motion connecting S, u, v and a where the symbols have their usual meanings. Answer: Ques

Probability Test 1) One number is drawn from numbers 1 to 150. Find the probability that it is either divisible by 3 or 5. 2) What is the probability that a letter selected at random in an English book is a vowel. 3) A number was drawn at random from the number 1 to 50. What is the probability that it will be a multiple of 2 or 3 or 10. 4) Suppose that it is 11 to 5 against a person A, who is 38 years of age living till he is 73 and 5 to 3 against a person B now 43 living till he is 78 years. Find the probability that both will die 35 years, hence. 5) A candidate is interviewed for the 3 posts. For the first post, there are 3 candidates, for the second post, there are 4 and for third there are 2. What are the chances that he will get selected? 6) Four cards are drawn without replacement. What is the probability that they are all aces? 7) Find the probability of 53 Sundays in a year selected at random. 8) Two unbiased dice are thrown. Find the probabili