s.a-2-exams-9th-class-P.S-key-papers
9TH CLASS SUMMETIVE ASSESSMENT-2 EXAMINATIONS APRIL 2024 PHYSICAL SCIENCE KEY PAPER
Prepared by,
P.Mallikarjuna Rao, S.A (P.S) GUNTUR
1. Oxygen < Water < Sugar.
2. B AND D
3. 8
4. meter per second squared or (ms−2) www.apteachers360.com
5. B
6. It is used in designing of ships and submarines..
It is used in lactometers to determine the purity of milk.
It is used in hydrometers to determine density of fluids.
It is used in lactometers to determine the purity of milk.
It is used in hydrometers to determine density of fluids.
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7. The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside.
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8. 
9. MOLAR MASS OF HCL = 36.5 g/mol
MOLAR MASS OF HNO3 = 63 g/mol
MOLAR MASS OF H2O = 18 g/mol
MOLAR MASS OF C2H2 = 26 g/mol
10. What is the main difference between speed and velocity? How do you calculate speed and velocity, and how are they used in different contexts?
11. The earth and the moon experience equal gravitational forces from each other. However, the mass of the earth is much larger than the mass of the moon. Hence, its acceleration towards the moon is much smaller than the acceleration of the moon towards the Earth. For this reason, the Earth does not move towards the moon.
P.Mallikarjuna Rao, S.A (P.S) GUNTUR
12. (A) 
12 (B) www.apteachers360.com
15. (A) Sound is produced due to vibrations. When a body vibrates, it forces the adjacent particles of the medium to vibrate.
16) A) Atomic Number:
13. A) a) 2m/s
b) 0
c) frictional force acting opposite to applied force.
Gravitational force acting vertically downwards
normal force acting opposite to gravitational force.
d) straight line passing through origin.
14. The universal law of gravitation explains many phenomena that were believed to be unconnected:
(i) The motion of the moon round the earth
(ii) The responsibility of gravity on the weight of the body which keeps us on the ground
(iii) The tides because of the moon and therefore the Sun
(iv) The motion of planets round the Sun
This results in a disturbance in the medium, which travels as waves and reaches the ear. Hence, the sound is produced.
It is produced from a vibrating body. The vibrating body causes the medium (water, air, etc.) around it to vibrate thus producing sound. The sound is produced when something vibrates . Sound waves consist of areas of high and low pressure called compressions and rarefactions, respectively. Vibrations that travel through the air or another medium, can be heard when they reach a person's or animal's ear.
(OR)
15) B) Kinetic energy is the energy of motion, observable as the movement of an object, particle, or set of particles.
Examples of Kinetic Energy:
1. An airplane has a large amount of kinetic energy in flight due to its large mass and fast velocity.
2. A baseball thrown by a pitcher, although having a small mass, can have a large amount of kinetic energy due to its fast velocity.
3. A downhill skier traveling down a hill has a large amount of kinetic energy because of their mass and high velocity.
4. A golf ball sitting on a tee before it is struck has zero kinetic energy because its velocity is zero.
5. An asteroid falling to earth at incredible speeds has an enormous amount of kinetic energy.
6. A car traveling down the road has less kinetic energy than a semi-truck traveling at the same speed because the car's mass is much less than the truck's.
7. A river flowing at a certain speed possesses kinetic energy because the water has a certain mass and it also has velocity.
8. An insect flying has a small amount of kinetic energy because its mass and velocity are relatively small.
1. An airplane has a large amount of kinetic energy in flight due to its large mass and fast velocity.
2. A baseball thrown by a pitcher, although having a small mass, can have a large amount of kinetic energy due to its fast velocity.
3. A downhill skier traveling down a hill has a large amount of kinetic energy because of their mass and high velocity.
4. A golf ball sitting on a tee before it is struck has zero kinetic energy because its velocity is zero.
5. An asteroid falling to earth at incredible speeds has an enormous amount of kinetic energy.
6. A car traveling down the road has less kinetic energy than a semi-truck traveling at the same speed because the car's mass is much less than the truck's.
7. A river flowing at a certain speed possesses kinetic energy because the water has a certain mass and it also has velocity.
8. An insect flying has a small amount of kinetic energy because its mass and velocity are relatively small.
(i) The number of positively charged protons present in the nucleus of an atom is defined as the atomic number and is
denoted by Z. Example: Hydrogen has one proton in its nucleus; hence, its atomic number is one.
ii) Mass number:
(ii) The total number of protons and neutrons present in the nucleus of an atom is known as the mass number. It is
denoted by A. 20Ca40. The mass number is 40. The atomic number is 20.
Isotopes:
(iii) The atoms which have the same number of protons but a different number of neutrons are referred to as isotopes.
Hence, the mass number varies.
Example: The most simple example is the Carbon molecule which exists as 6C12 and 6C14
(iv) Isobars:
Isobars are atoms which have the same mass number but differ in atomic number. Examples are, 20Ca40 and 18Ar40
(OR)
16) B) 
17) A) Any relevant experiment
Newton's third law of motion states that for every action there is an equal and opposite reaction. These action-reaction forces act on two different bodies.
(OR)
1. Take 5 ml of water in a test tube and keep it near a window or under a fan.
2. Take 5 ml of water in an open china dish and keep it near a window or under a fan.
3. Take 5 ml of water in an open china dish and keep it inside a cupboard or on a shelf in your class.
4. Record the room temperature.
5. Record the time or days taken for the evaporation process in the above cases.
6. Repeat the above three steps of activity on a rainy day and record your observations.
Observation and conclusion:
If the surface area is increased, the rate of evaporation increases.
If the amount of water in air is already high, the rate of evaporation decreases.
If wind speed is increased, rate of evaporation increases.
Prepared by,
P.Mallikarjuna Rao.
S.A (P.S) GUNTUR.