Jagranjosh presents CBSE Class 9th Science Solved Practice Paper for SA – I, 2016-17. This practice paper is specially prepared at jagranjosh.com after the brief analysis of previous year SA ‒ I question papers.
About CBSE Science Paper for SA – I: 2016-17
Most of the schools set CBSE Class 9th Science SA – I papers as per the examination pattern issued by CBSE board. However, level of questions in the question paper varies from school to school. Despite the variations in level of questions asked in the question papers set by different CBSE schools, there are some common questions which are asked in various schools frequently. This practice paper gives you an idea of such common questions. All the questions in practice paper are provided with detailed explanation.
Importance of CBSE Class 9th Practice Paper:
This Science SA – I solved practice paper is set as per the latest CBSE exam pattern. The questions asked in this paper will give you a fair idea of the important topics to be studied for SA-I, 2016-17 and help you score optimum. There are dictated unique solutions to all the questions. These solutions will give you a clear idea about what and how much must be written in the Class 9th Science SA – I examination 2016 – 17 to fetch you the maximum score.
After going through this paper you will:
• understand the latest examination pattern
• know important questions likely to be asked in SA – I Science exam
• learn to give proper explanations to the questions
• learn time management
Some of the sample questions from the practice paper are:
Q. At which temperature the solid and liquid states of a substance can exist together?
Ans. The temperature at which solid and liquid states of a substance can exist together is known as freezing point.
Q. When a potted plant is covered with a glass jar, why do the water vapours appear on the walls of the jar?
Ans. The epidermis of the leaf has small pores which are known as stomata. These stomata are enclosed by kidney-shaped cells called guard cells. These cells are responsible for exchange of gases with the atmosphere. So when a potted plant is covered with a glass jar, plants are losing water in the form of water vapour through stomata. This process is known as transpiration and hence water vapour appears on the walls of the jar.
Q. Water is a compound not a mixture. Justify the statement.
Ans. A mixture consists of more than one kind of pure form of matter which are not in fixed compositions. These pure forms of matters can be separated from one another by a physical process. A mixture demonstrates the properties of constituent substances. A compound on the other hand has substances in their pure form which are chemically combined in fixed compositions. The compound has totally different properties from that of its constituents. These constituents cannot be separated by some physical process. In case of water, the constituent’s hydrogen and oxygen are always found in the ratio 2:1. These pure substances can neither be separated from water nor their composition can be altered by any physical method. Also water exhibits totally different properties from its constituents. Therefore, it can be clearly inferred here that water is compound not mixture as it exhibits all the properties of compound.
Q. A scooter after applying the brakes, moves with a velocity of 15 m/s when brakes are applied. If the mass of the scooter and the rider is 160 kg. and the constant force applied by the brakes is 500N then calculate: (a) Time for which the brakes should be applied to make the scooter come to a halt (b) Distance travelled by the scooter before it comes to rest.
Ans. The initial velocity of the scooter, u = 15m/s
Here final velocity of scooter will be, v = 0 m/s
The mass of the scooter is 160 kg and force applied with brakes is 500N
So acceleration of the body can be calculatred as:
From Newton’s second law of motion we have, F = ma
⟹ a = F/m = 500/160 =3.125 m/s2
We know, v = u + at
But since brakes are being applied therefore acceleration will be in direction opposite to that of motion.
Hence, v = u − at
0 = 15 − 3.125 t
Solving the above equation, we get
t = 4.8
Now, using the third equation of motion we get:
v2 = u2 − 2as
2as = u2
225 = 2 × 4.8 × s
s = 23.4375 m
Q. Comment on the following statements:
(a) Rate of evaporation is high when the humidity of air is low.
(b) Steam causes severe burns than boiling water.
(c) Sponge can be pressed easily; still it is a solid.
(d) Sugar crystals dissolve faster in hot water than cold water.
(e) Fragrance of an incense stick lighted in the corner of a room, spreads throughout the room.
Ans.
(a) Humidity is a measure of water vapour in the atmosphere. The atmosphere is capable of holding a fixed amount of water vapour at a particular temperature. With a rise in humidity, the rate of evaporation decreases and also with low humidity the evaporation rate is high.
(b) The molecules of steam have supplementary energy than water at the same temperature. This energy is present due to absorbed energy in the form of latent of vaporization and that’s why steam causes severe burns than boiling water.
(c) Sponge comprises of small or minute holes which trap air in them. When the sponge is pressed, the air is expelled out and sponge is pressed easily despite being solid in nature.
(d) When we dissolve sugar crystals in water, the molecules of sugar take the space between the molecules of water and hence sugar disappear. When we heat the water, we observe that sugar takes less time to dissolve. Reason to this behavior is that the particles of matter are continuously in motion. This implies that the particles of matter have kinetic energy. As we increase the temperature, the kinetic energy of the molecules also increases and hence the particles of sugar take less time to mix into water.
(e) Air around us has particles which have space between them. When we light the incense stick, it burns to give out fragrant smoke. The smoke particles are at high kinetic energy due to the heat being generated by the burring of incense. These high energy particles of smoke start taking space between the particles of air and hence the fragrance spreads.
