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Rare-earth elements are exhibited by_______.

(A) Atomic numbers 21 to 30. (B) Atomic numbers 39 to 71. (C) Atomic numbers 58 to 71. (D) Atomic numbers 81 to 91. The Correct Answer is (C)... View Article

What do you understand about the term non-stoichiometric hydrides? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.

Solution: In non-stoichiometric hydrides, the ratio of the metal to hydrogen is fractional and does not correspond to the actual formula. Their... View Article

The circumference of the second orbit of an atom or ion having single electron is 4 * 10-9 m. The de-Broglie wavelength of electron revolving in this orbit should be

(A) 1 * 10-9 m (B) 2 * 10-9 m (C) 4 * 10-9 m (D) 8 * 10-9 m The Correct Answer is (B) 2 * 10-9 m Solution: As given in the question: The... View Article

What happens to the half-life period for a first-order reaction, if the initial concentration of the reactants is increased?

(A) Increases (B) Decreases (C) Remains unchanged (D) Increases and then decreases. The Correct Answer is (C) Remains unchanged Solution:... View Article

Assertion: P-Nitro phenol is a stronger acid than O-nitro phenol. Reason: Intramolecular hydrogen bonding makes ortho – isomer weaker acid than para – isomer.

(A) Both Assertion and Reason are false. (B) Assertion is true, but Reason is false. (C) Both Assertion and Reason are true. The reason is... View Article

If m times the mth term of an A.P. is equal to n times nth term, then (m+n)th term of the A.P is ____.

If m times the mth term of an A.P. is equal to n times nth term, then (m+n)th term of the A.P is zero. Explanation: According to the nth term... View Article

What is the integral of sin^4 (x) dx?

Assume that, I = ∫ sin4x dx Now, reduce sin4x dx to integrate the function. I = ∫ (sin2x)2 dx As we know 2sin2x = 1 - cos2x, Put... View Article

What is transitive relations. Give an example

In set theory, a transitive relation is a binary relation. If a relation R on set A is said to be a transitive relation, if (a, b) ∈ R and... View Article

Three men paint a house in 20 days. How many days do 30 men take to do the same?

Given that, 3 men paint a house in 20 days. Now, we have to find the number of days, when 30 men take to do the same work. Let x be the no.... View Article

Out of 80 students 45%, students passed in Mathematics and 60% students passed in English. If 35% students failed in both the subjects, how many students passed in both the subjects?

Given that the total number of students = 80 45% students passed in Mathematics = (45/100)80 = 36 students passed in Mathematics 60% students... View Article

A dice is rolled twice. Find the probability that 5 will not come up either time.

If a die is rolled twice, the total number of outcomes is 36. S = {(1,1)(1,2)(1,3)(1,4)(1,5)(1,6) (2,1)(2,2)(2,3)(2,4)(2,5)(2,6)... View Article

Write a square – b square formula.

The formula for a square - b square is given as:a2 - b2 = (a - b)(a + b)... View Article

Prove that angles opposite to equal sides of an isosceles triangle are equal.

Given:An isosceles triangle ABC where AC = BC.To prove: ∠CAB = ∠CBA.Construction:CD, the bisector of ∠ACB. Proof:Now in ∆ACD and ∆BCD... View Article

1 trillion is how many billion?

Billion = 1,000,000,000Ten billion - 10,000,000,000Hundred billion - 100,000,000,000Trillion - 1,000,000,000,000That means, 1 trillion is 1000 billion.... View Article

What is the value of 21 cube?

21 cube can be written as (21)3.(21)3 = 21 × 21 × 21(21)3 = 9261Therefore, the value of the 21 cube is 9261.... View Article

Find the HCF of 170 and 238 using prime factorization of 170 and 238.

The prime factorization of 170 = 2 × 5 × 17 The prime factorization of 238 = 2 × 7 × 17HCF of 170 and 238 = 2 × 17 = 34... View Article

Write any three different forms of the formula (a + b)^2.

We know that,(a + b)2 = a2 +b2 + 2abIn mathematics, the algebraic identity (a + b)2 can be defined in different three ways as given below.1. The... View Article

Use the divisibility rule to check the divisibility of 23457 by 4.

The divisibility rule of 4 states that if the last two digits of the number is divisible by 4 or 00, the number will be divisible by 4.Given... View Article

What is the prime factorization of 3780?

Prime factorization of 3780 = 2 x 2 x 3 x 3 x 3 x 5 x 7= 22 × 33 × 51 × 71... View Article

If r = 7 cm and θ = 60°, then find the perimeter of the minor sector.

Given,r = 7 cmθ = 60°Perimeter of the minor sector = 2r + (θ/360°) 2πr= 2(7) + (60°/360°) × 2 × (22/7)... View Article

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