Sujeet Kumar

Textbook Questions and Answers 1. Give examples. a. Positive radicalsAnswer:Na+– Sodium ion, K+ – Potassium ion b. Basic radicalsAnswer:Na+ – Sodium ion, K+ – Potassium ion, Ag+ – Silver ion c. Composite radicalsAnswer: d. Metals with variable valencyAnswer:(a) Iron (Ferrum)(i) Fe2+ – Ferrous [Iron – II](ii) Fe3+ – Ferric [Iron – III] (b) Copper (Cuprum)(i) Cu+ – Cuprous [Copper -1](ii) Cu2+ – Cupric … Read more

Textbook Questions and Answers 1. The accompanying figure shows some electrical appliances connected in a circuit in a house. Answer the following questions. A. By which method are the appliances connected?Answer:Appliances are connected in parallel. B. What must be the potential difference across individual appliances?Answer:The potential difference across all appliances is same in parallel connection. … Read more

Textbook Questions and Answers 1. Write detailed answers? a. Explain the difference between potential energy and kinetic energy.Answer: Kinetic Energy Potential Energy (i) Kinetic energy is the energy possessed by the body due to its motion. (i) Potential energy is the energy possessed by the body because of its shape or position. (ii) K.E = … Read more

Textbook Questions and Answers 1. Match the first column with appropriate entries in the second and third columns and remake the table. 2. Clarify the differences A. Distance and displacementAnswer: Distance Displacement (i) Distance is the length of the actual path travelled by an object.(ii) It is a scalar quantity.(iii) It is either equal to … Read more

Question 1.If diameter of a road roller is 0.9 m and its length is 1.4 m, how much area of a field will be pressed in its 500 rotations? ( π =22/7)Given: For road roller,diameter (d) = 0.9 m, length (h) = 1.4 mTo find: Area of a field pressed in 500 rotationsSolution:i. Since, area … Read more

Question 1.Find the surface areas and volumes of spheres of the following radiii. 4 cmii. 9 cmiii. 3.5 cm (π = 3.14)i. Given: Radius (r) = 4 cmTo find: Surface area and volume of sphereSolution: ii. Given: Radius (r) = 9 cmTo find: Surface area and volume of sphereSolution:Surface area of sphere = 4πr2= 4 … Read more

Question 1.Perpendicular height of a cone is 12 cm and its slant height is 13 cm. Find the radius of the base of the cone.Given: Height (h) = 12 cm, length (l) = 13 cmTo find: Radius of the base of the cone (r)Solution:l2 = r2 + h2∴ 132 = r2 + 122∴ 169 = r2 + 144∴169 – 144 … Read more

Question 1.Length, breadth and height of a cuboid shape box of medicine is 20 cm, 12 cm and 10 cm respectively. Find the surface area of vertical faces and total surface area of this box.Given: For cuboid shape box of medicine,length (l) = 20 cm, breadth (b) = 12 cm and height (h) = 10 … Read more

Question 1.Choose the correct alternative answer for the following multiple choice questions. i. Which of the following statements is true?(A) sin θ = cos (90 – θ)(B) cos θ = tan (90 – θ)(C) sin θ = tan (90 – θ)(D) tan θ = tan (90 – θ)Answer:(A) sin θ = cos (90 – θ) … Read more

Question 1.In the following table, a ratio is given in each column. Find the remaining two ratios in the column and complete the table. Solution:In right angled ∆ABC,∠C = θ.Let the common multiple be k.∴ BC = 35k and AC = 37kNow, AC2 = AB2 + BC2 …[Pythagoras theorem]∴ (37k)2 = AB2+ (35k)21369k2 = AB2 + 1225k2AB2 = 1369k2 – 1225k2= 144k2AB … Read more