Q. What is the minimum frequency of sound waves needed to prepare emulsion from two immiscible liquids?

Q. Draw a neat diagram of petrol engine and label the following parts :
a) Piston b) Spark plug c) Crank shaft

Q. Write two differences between centripetal force and centrifugal force.

Q. The defect in an engine is detected by using X-rays. The gamma radiation can also be used for the same purpose because gamma radiation has

1. Higher wavelength than X-ray
2. Same frequency as that of X-ray
3. Same wavelength as that of X-ray
4. Higher frequency than X-ray

Q. Explain the method of extractioin of amorphous silicon using silica.

Q. What is induced radioactivity ? Name the radioactive element obtained when ${}_{13}A{l}^{27}$ is bombarded with alpha particle. Write one use of this radioactive element.

Q. Name of the simplest hydrocarbon is _____________.

Q. A robot sent to the moon sends a laser light towards the earth. If it takes $13$ seconds to reach the earth then calculate the distance between moon and the earth in kilometres.
(Given : Velocity of light is $3\times {10}^{8}m/s$)

Q. What is Saponification?

Q. The transducer used in television transmission works on the principle of

1. Rayleigh's effect
2. Electromagnetic induction
3. Photoelectric effect
4. Raman's effect

Q. Match the colour of stars in List - A with the stars in List - B. Write the correct answer in the space provided

Q. By how many times a $3rd$ magnitude star is brighter than $5th$ magnitude star?

Q. Draw a neat diagram showing the permutit process of softening hard water and label the following:
a) Zeolite layer b) Soft water layer

Q. Draw a neat diagram of $AC$ dynamo and label the parts.

Q. The ratio of number of moles of butane to the number of moles of oxygen necessary for complete combustion of butane is:

1. $1:2$
2. $2:3$
3. $1:5$
4. $2:13$

Q. The induced electromotive force increases when a magnet is moved fast in a stationary coil of wire because

1. Rate of change of magnetic field increases
2. Magnetic field increases
3. Rate of change of magnetic field decreases
4. Magnetic field decreases

Q. Which reaction is responsible for solar energy? Name the major component of solar energy that reaches us.

Q. Write two differences between intrinsic semiconductor and extrinsic semiconductor.

Q. Human beings are interfering in bio-geochemical cycle by using

1. Soaps
2. Detergents
3. Paper
4. Cotton

Q. The source that gives line emission spectrum when subjected to dispersion is

1. Molten iron
2. Candle flame
3. Sun
4. Mercury vapour

Q. Which of the following is not a good practice to conserve fuel?

1. Using public transport system
2. Using motor bike to travel short distances
3. Using bicycle to travel short distances
4. Walking the short distances

Q. A composite light containing yellow, blue and orange colours is passed through a prism. Which colour bends the most?

Q. Two masses $m_1$ and $m_2$ are separated by a distance $d$. Find by how many times the force of gravity increases if mass of each of the objects is doubled without change in the distance between them.

Q. Calcium bicarbonate causes hardness in water but not calcium carbonate. Why?

Q. A photoelectric cell emits electrons when illuminated by a $60W$ bulb. If the same cell is illuminated by replacing it with a $40W$ bulb, the observation that can be made is

1. No photoelectric effect takes place
2. Number of photoelectrons increases
3. The kinetic energy of photoelectrons decreases
4. Number of photoelectrons decreases

Q. If $I$ is the intensity of scattered light of wavelength $\lambda$. then relation between them is given by:

1. $I\propto \frac{1}{{\lambda }^4}$
2. $I^2\propto \frac{1}{{\lambda }^4}$
3. $I\propto {\lambda }^4$
4. $I\propto \frac{1}{\lambda }$

Q. What is a heat engine?

Q. Draw a neat diagram of electrolytic cell used in the purification of copper and label the following:
a) Anode b) Cathode

Q. The gravitational force between earth and an object of mass $10kg$ on its surface in newtons is ____________

Q. $A,B$ and $C$ are the three coils of conductor having different number of turns, wound around a soft iron ring as shown in the figure. Ends of coils $B$ and $C$ are connected to the galvanometers. The observation that can be made when ends of coil $A$ are connected to an A.C. source is

1. Same electric current is induced in $B$ and $C$
2. No electric current is induced in $B$ and $C$
3. Induced electric current is more in $B$ than in $C$
4. Induced electric current is less in $B$ than in $C$