CBSE ADDA

Q. Find the gram molecular mass of water (H2O) Calculation: 2(H) = 2 x 1 = 2 . 1(O) = 1 x 16 = 16 ∴ Gram molecular mass of H2O= 18g Mole is defined as the amount of substance that contains as many specified elementary particles as the number of atoms in 12g of carbon-12 isotope. One mole is also defined as the amount of substance which contains Avogadro number (6.023 x 10^23) of particles. For eg. one mole of oxygen atoms represents 6.023 x 10^23 atoms of oxygen and 5 moles of oxygen atoms contain 5 x 6 . 0 2 3 x 10 ^23 a t oms of oxygen . Q. Calculate the number of aluminium ions present in 0.051 g of aluminium oxide. [Hint : The mass of an ion is same as that of an atom of the same element. Sol: 1 mole of Al2O3 contains aluminium ions = 2 × 6.022 × 10^23 = 12.044 × 10^23 Now, 102 g of Al2O3 has number of aluminium ions = 12.044 × 10^23 0.051 g of Al2O3 has number of aluminium ions = (12.044 ×1023 × 0.051)/102= 6.022 × 10^20 ions Q. How many atoms of oxygen are present i

Q1 The first three terms of an AP respectively are  3y – 1, 3y + 5 and 5y + 1. Then y equals: (A) –3 (B) 4 (C) 5 (D) 2 Solution: (C) 5 Q2 In Fig. 1, QR is a common tangent to the given circles, touching externally at the point T. The tangent at T meets QR at P. If PT = 3.8 cm, then the length of QR (in cm) is : (A) 3.8 (B) 7.6 (C) 5.7 (D) 1.9 Solution: (B) 7.6 Q3 In Fig. 2, PQ and PR are two tangents to a circle with centre O. If ∠QPR = 46°, then ∠QOR equals: (A) 67° (B) 134° (C) 44° (D) 46° Solution: (B) 134° Q4. A ladder makes an angle of 60° with the ground when placed against a wall. If the foot of the ladder is 2 m away from the wall, then the length of the ladder (in metres) is: (A) 43 (B) 43 (C) 22 (D) 4 Solution: (D) 4 Q5 If two different dice are rolled together, the probability of getting an even number on both dice, is: (A) 136 (B) 12 (C) 16 (D) 14 Solution: (D) 14 Q6 A number is selec

SECTION A All questions are similar in 30/2 set                             SECTION B All questions are similar in 30/2 set except Q.No. 14 14. Find the value of p so that p x (x-3)+9 = 0 has equal roots. SECTION C All questions are similar in 30/2 set except Q. No. 20,22,23,24 20. Construct a triangle with side 5 cm, 5.5 cm and 6.5 cm . Now construct another triangle, whose sides are 3/5 times the corresponding sides of given triangle. 22. The sum of first seven term of AP is 182. If 4th and 17th term are in ratio 1: 5 . Find AP 23.From the top of 60m high building , the angle of depression of the top and bottom of a tower are 45 deg. and 60 deg. respectively. Find the height of tower. 24.Find a point p on y axis which is equidistant from points A(4,8)and B(-6,6) SECTION D All questions are similar in 30/2 set except Q.No.31, 32 and 34 31. (x – 4) / (x – 5 )/ (x – 6) / (x – 7 ) = 10/3 32. Five cards – the ten, jack ,queen king and ace of diamonds are are well

Series HRS Code-30/2 Summative Assessment –II Subject Mathematics class 10 CBSE Board 2014 SECTION-A 1. The probability that a number selected at random from the number 1,2,3,…..15. is a multiple of 4 is (A)4/15 (B) 2/15 (C)1/5 (D)1/3 Ans: 1/5 2. The angle of depression of car parked on the road from the top of a 150m high tower is 300 . The distance of the car from the tower in m meter is (A)50Ö3 (B)150Ö3 (C) 50Ö2 (D)75 Ans: (B)150Ö3 3. Two circle touches externally at P . AB is common tangent to the circle touching them at A and B . The value of <APB is (A)300 (B)450 (C)600 (D) 900 Ans: (B)450 4. If k,2k -1 and 2k + 1 are three consecutive term of AP then value of k is (A)2 (B)3 (C)-3 (D)5 Ans: (B)3 5. A chord of a circle of