The gravitational force between two objects becomes _______ when the masses of both objects are halved without altering the distance between them.

(a)

\(\frac{f}{4}\)

(b)

\(\frac{f}{2}\)

(c)

f

(d)

2f

A small bulb is placed at the principal focus of a convex lens. When the bulb is switched on, the lens will produce

(a)

a convergent beam of light

(b)

a divergent beam of light

(c)

a parallel beam of light

(d)

a coloured beam of light

Absolute scale is also called as ______

(a)

Kelvin scale

(b)

Celsius scale

(c)

Centigrade scale

(d)

Fahrenheit scale

The main source of stellar energy is
(i) fission reactors
(ii) fusion reaction
(iii) chemical reaction
(iv) thermonuclear reactions

(a)

(i) is correct

(b)

(i) & (ii) are correct

(c)

(i) & (iv) are correct

(d)

(ii) & (iv) are correct

Which of the following has the smallest mass?

(a)

6.023 × 10²³ atoms of He

(b)

1 atom of He

(c)

2 g of He

(d)

1 mole atoms of He

Which of the following is the pair of shortest and longest periods in the modern periodic table?

(a)

1^st, 2^nd

(b)

2^nd, 3^rd

(c)

5^th, 7^th

(d)

1^th, 6^th

A solution is a __________ mixture.

(a)

homogeneous

(b)

heterogeneous

(c)

homogeneous and heterogeneous

(d)

non homogeneous

The animals which give birth to young ones are

(a)

Oviparous

(b)

Viviparous

(c)

Ovoviviparous

(d)

All the above

Sneezing, yawning etc are examples of _______

(a)

voluntary actions

(b)

involuntary actions

(c)

reflex actions

(d)

planned actions

The best way of direct dating fossils of recent origin is by

(a)

Radio-carbon method

(b)

Uranium lead method

(c)

Potassium-argon method

(d)

Both (a) and (c)

Which is used to edit programs?

(a)

Inkscape

(b)

script editor

(c)

stage

(d)

sprite

While catching a cricket ball the fielder lowers his hands backwards. Why?

Write the difference between ammeter and voltmeter.

Name three animals, which can hear ultrasonic vibrations.

Write the different types of isotopes of oxygen and its percentage abundance.

Classify the following substances into deliquescent, hygroscopic. Conc. Sulphuric acid, Copper sulphate pentahydrate, Silica gel, Calcium chloride, and Gypsum salt.

List the difference between Dicot and Monocot stem.

How does leech suck blood from the host?

Explain the Theory of Special Creation.

What is metastasis?

What is Scratch?

Explain the working of the eye.

Find the final temperature of a copper rod. Whose area of cross section changes from 10 m² to 11 m² due to heating. The copper rod is initially kept at 90 K. (Coefficient of superficial expansion is 0.0021 /K)

Explain the uses of radio isotopes in medicine field?

Give the balanced chemical equation of the following reactions:
(i) Neutralization of NaOH with ethanoic acid.
(ii) Evolution of carbon dioxide by the action of ethanoic acid with NaHCO₃.
(iii) Oxidation of ethanol by acidified potassium dichromate.
(iv) Combustion of ethanol.

Why is the Sinoatrial node called the pacemaker of heart?

How are chromosomes classified based on the position of centromere?

The degenerated wing of a kiwi is an acquired character. Why is it an acquired character?

Name three improved characteristics of wheat that helped India to achieve high productivity.

What is diabetes? Explain the types.

Program for print the word “Hello” with sound

1. Will the cool drinks give more fizz at top of the hills or at the foot? Explain.

2. Polyploids are characterised by gigantism. Justify your answer.

1. A heavy truck and bike are moving with the same kinetic energy. If the mass of the truck is four times that of the bike, then calculate the ratio of their momenta. (Ratio of momenta = 2:1)

2. A plant hormone was first discovered in Japan when rice plants were suffering from Bakanae disease caused by Gibberella fujikoroi. Based on this information answer the following questions:
   a) Identify the hormone involved in this process.
   b) Which property of this hormone causes the disease?
   c) Give two functions of this hormone.

1. Metal A belongs to period 3 and group 13. A in red hot condition reacts with steam to form B. A with strong alkali forms C. Find A, B and C with reactions. (or) Metal belongs to 3rd period and 13th group in the modern periodic table of elements. A reacts with steam in red hot condition to form compound B. A also reacts with strong alkali (NaOH) to form conpound C. Find A, B and C. Write appropriate balance chemical equations.

2. Can a nickel spatula be used to stir copper sulphate solution? Justify your answer.