**MCQs Questions for Class 11 Maths Chapter 5 Complex Numbers and Quadratic Equations**

In this 21^{st} century, Multiple Choice Questions (MCQs) play a vital role to prepare for a competitive examination. CBSE board has also brought a major change in its board exam patterns. Now-a-days, a total of 10 MCQs questions are asked in the class 10 board examination.

In most of the competitive examinations, only MCQ questions are asked. So, for getting ready for the competitive examinations, we have to practice for MCQs questions to solve. It strengthens the critical thinking and problem solving skills.

In future, if you want to prepare for competitive examination and to crack it, then you should more focus on the MCQ questions. Thus, from the board examinations point of view and competitive examinations point of view, you should practice more on multiple choice questions.

Thus, let’s solve these MCQs Questions to make our foundation very strong.

**MCQs Questions for Class 11
Maths Chapter 5 Complex Numbers and Quadratic Equations**

**1.** The value of
√(-81) is

(a) -9i

(b) 9i

(c) -3i

(d) 3i

**Answer: b**

**2.** In a
complex number, z = 4 + i, what is the real part?

(a) 4

(b) i

(c) 1

(d) 4 + i

**Answer: b**

**3. **The value of
√(-144) is

(a) 12i

(b) -12i

(c) ±12i

(d) None of these

**Answer: a**

**4. **If
(x + 3) + i(y – 2) = 5 + 2i, then find
the values of x and y.

(a) x = 8 and y = 4

(b) x = 2 and y = 4

(c) x = 2 and y = 0

(d) x = 8 and y = 0

**Answer: b**

**5. **If z lies on |z| = 1, then 2/z lies on

(a) a circle

(b) an ellipse

(c) a straight line

(d) a parabola

**Answer: a**

**6. ** If z_{1} = 2 + 3i
and z_{2} = 5 + 2i, then find the sum of two complex
numbers.

(a) 4 + 8i

(b) 3 – I

(c) 7 + 5i

(d) 7 – 5i

**Answer: c**

**7. **If Ï‰ is an imaginary cube root of unity, then
(1 + Ï‰ – Ï‰²)^{7} equals

(a) 128 Ï‰

(b) -128 Ï‰

(c) 128 Ï‰²

(d) -128 Ï‰²

**Answer: d**

**8. **-z is _________________ for the complex number
z.

(a) additive inverse

(b) additive identity element

(c) multiplicative identity element

(d) multiplicative inverse

**Answer: a**

**9. **The least value of n for which {(1 + i)/(1 –
i)}^{n} is real, is

(a) 1

(b) 2

(c) 3

(d) 4

**Answer: b**

**10. **1/z is _________________ for complex number z.

(a) additive inverse

(b) additive identity element

(c) multiplicative identity element

(d) multiplicative inverse

**Answer: d**

**11. **The value of i^{-999} is

(a) 1

(b) -1

(c) i

(d) -i

**Answer: c**

**12. **If z_{1} = 8 + 5i
and z_{2} = 3 + 6i, then find the value of z_{1 }– z_{2}.

(a) -5 + i

(b) 5 – i

(c) 5 + i

(d) 5 – 5i

**Answer: b**

**13. **The complex numbers sin x + i cos 2x and sin x – i cos 2x are
conjugate to each other for

(a) x = nÏ€

(b) x = 0

(c) x = (n + 1/2) Ï€

(d) no value of x

**Answer: d**

**14. ** In the complex number, z = 5 + 2i, what
is the imaginary part?

(a) 5

(b) 2i

(c) 5 + 2

(d) 5 + 2i

**Answer: b**

**15. **The value of x and y if (3y – 2) + i(7 – 2x) =
0 is

(a) x = 7/2, y = 2/3

(b) x = 2/7, y = 2/3

(c) x = 7/2, y = 3/2

(d) x = 2/7, y = 3/2

**Answer: a**