List of top Questions asked in CBSE Class X

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients.

(i) \(x^2 – 2x – 8\) (ii) \(4s^2 – 4s + 1\) (iii) \(6x^2 – 3 – 7x\) (iv) \(4u^2 + 8u\) (v) \( t^2 – 15\) (vi) \(3x^2 – x – 4\)

Write the balanced chemical equation for the following and identify the type of reaction in each case.
(a) Potassium bromide(aq) + Barium iodide(aq) \(→\) Potassium iodide(aq) + Barium bromide(s)
(b) Zinc carbonate(s) \(→\) Zinc oxide(s) + Carbon dioxide(g)
(c) Hydrogen(g) + Chlorine(g) \(→\) Hydrogen chloride(g)
(d) Magnesium(s) + Hydrochloric acid(aq) \(→\) Magnesium chloride(aq) + Hydrogen(g)

Prove that the following are irrationals :

\(\dfrac{1}{\sqrt 2}\)
\(7\sqrt 5\)
\(6 + \sqrt 2\)

Who does Lencho have complete faith in? Which sentences in the story tell you this?

Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.

How does Anne feel about her father, her grandmother, Mrs Kuperus and Mr Keesing? What do these tell you about her?

What kind of a person do you think the narrator, a veterinary surgeon, is? Would you say he is tactful as well as full of common sense?

Did you begin to suspect, before the end of the story, that the lady was not the person Horace Danby took her to be? If so, at what point did you realise this, and how?

Fill in the blanks in the following table, given that a is the first term, d the common difference and an the nth term of the AP:

	a	d	n	\(a_n\)
(i)	7	3	8	….
(iI)	-18	…	10	0
(iii)	…	-3	18	-5
(iv)	-18.9	2.5	…	3.6
(v)	3.5	0	105	…

The table below shows the daily expenditure on food of 25 households in a locality

Daily expenditure (in Rs)	100 - 150	150 - 200	200 - 250	250 - 300	300 - 350
Number of households	4	5	12	2	2

Find the mean daily expenditure on food by a suitable method.

Do you think there are also parents like Mrs. Pumphrey?

Explain the following terms with one example each.
(a) Corrosion
(b) Rancidity

The following frequency distribution gives the monthly consumption of electricity of 68 consumers of a locality. Find the median, mean and mode of the data and compare them

Monthly consumption (in units)	Number of consumers
65 - 85	4
85 - 105	5
105 - 125	13
125 - 145	20
145 - 165	14
165 - 185	8
185 - 205	4

A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?

How did Mandela’s understanding of freedom change with age and experience?

A ladder has rungs 25 cm apart. (see Fig. 5.7). The rungs decrease uniformly in length from 45 cm at the bottom to 25 cm at the top. If the top and the bottom rungs are \(2\frac 12\) m apart, what is the length of the wood required for the rungs?

In a retail market, fruit vendors were selling mangoes kept in packing boxes. These boxes contained varying number of mangoes. The following was the distribution of mangoes according to the number of boxes.

Number of heartbeats per minute	50-52	53-55	56-58	59-61	62-64
Number of boxs	15	110	135	115	25

Find the mean number of mangoes kept in a packing box. Which method of finding the mean did you choose?

The angle of elevation of the top of a building from the foot of the tower is 30° and the angle of elevation of the top of the tower from the foot of the building is 60°. If the tower is 50 m high, find the height of the building.

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 10⁸ m s⁻¹.

Was Anne right when she said that the world would not be interested in the musings of a thirteen-year-old girl?

An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and the nature of the image.

Find the focal length of a convex mirror whose radius of curvature is 32 cm.

A student noted the number of cars passing through a spot on a road for 100 periods each of 3 minutes and summarised it in the table given below. Find the mode of the data :

Number of cars	0 - 10	10 - 20	20 - 30	30 - 40	40 - 50	50 - 60	60 -70	70 - 80
Frequency	7	14	13	12	20	11	15	8

A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?

Bholi’s real name is Sulekha. We are told this right at the beginning. But only in the last but one paragraph of the story is Bholi called Sulekha again. Why do you think she is called Sulekha at that point in the story?