**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. In most of the competitive examinations, only MCQ Questions are asked.

In future, if you want to prepare for competitive examination, then you should focus on the MCQs questions. Thus, let’s solve these MCQs questions to make our foundation strong.

In this post, you will find **15** **MCQs questions for class 11 maths chapter 5 complex numbers and quadratic equations**.

**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**