CBSE Sample Paper 9 2020-21 Science half yearly
Half Yearly Examination (2020-21)
Time Allowed- 3:00 hours
All questions are compulsory.
Multiple Choice Questions:-(7)
1- If the displacement of an object is proportional to square of time than the object moves with
a) uniform velocity
b) uniform acceleration
c) increasing acceleration
d) decreasing acceleration
2- slope of velocity time graph gives the
3- inertia of an object depends on its
b) mass and velocity
d) mass and acceleration
4- Rocket works on the principle of conservation of
5- On the surface of the earth, the value of g is
a) maximum at equator and minimum at poles
b) minimum at equator and maximum at poles
c) equal at all places
d) more at daytime and less at night time
6- The weight of an object at the centre of earth of radius R is
c) 1/R times the weight at the surface of the earth
d) R times the weight at the surface of the earth
7- An object exerts a normal force F on a surface of area A. Pressure p acting on the surface is
c) P= A/F
8- Answer these questions in brief:-(6)
a) Define uniform circular motion.
b) Why does a Karate expert suddenly reduce the speed of his hand while striking a slab of ice? Explain with reference to Newton’s law of motion.
c) Why object float or sink when placed on the surface of fluid. Give the conditions.
9- Answer these questions in detail:-(6)
a) Engine of a train exert a force of 6000 Newton. If total mass of the train and the engine be 18000 kilogram, and initially the train was standing on the platform ,what is the magnitude of velocity attained by the train 20 second after the start ?assume that there is no frictional force between railway track and the train and motion is in a horizontal direction.
b) Why does an athlete run for some distance before taking a jump?
13- Two balls A and B of mass m and 2m are in motion with velocity 2v and v respectively. Compare (4)
a) Their inertia
b) Their momenta
c) The force needed to stop them in the same time.
14- If the distance between two objects is increased 4 times, then by how many times will the mass of one of the object be changed to maintain the same gravitational force and also calculate the average density of the earth in terms of g, G and R. (5)
1- (3 marks)
a) Which assumption of Dalton’s atomic theory explain the law of constant proportion?
b) What is the difference between the molecule of an element and a molecule of a compound?
c) Calculate the percentage of oxygen in potassium dichromate K2Cr2O7.
2- (2 marks)
a) A 0.24 gm sample of a compound of carbon and oxygen on analysis was found to contain 0.096 gm of carbon and 0.144 gm of oxygen. Find the percentage composition of the compound by weight.
b) Calculate the number of molecules of Methane and number of carbon and hydrogen atoms in 25 gm of Methane.
3- Vitamin C contains three elements i.e. carbon, hydrogen and oxygen. Analysis of pure vitamins C shows that these elements are present in the following mass percentage : C= 40.9 % ,H= 4.58% and O= 54.5% .Determine the simplest formula of Vitamin C. (2)
4- Write the chemical formula and calculate the molecular mass of given compound: 1.baking soda 2.Washing soda 3.Blue vitriol 4.Oil of vitriol 5.Vinegar 6.Potash alum 5
5- Define distillation. What type of mixtures can be separated by distillation? Draw a labelled diagram of the Apparatus used for fractional distillation. 5
6- (5 marks)
a) Explain why particles of a colloidal solution don’t settle down when left and distributed.
b) How will you separate a mixture of sodium chloride and Iodine?
7- Identify solute and solvent in 80% solution of ethyl alcohol with water.(1)
8- Why is crystallization technique better than evaporation technique? (1)
9- What is the effect of temperature on the solubility of a solid in a liquid?(1)
10- Name the scientist who discovered chromatography technique.(1)
Multiple choice questions. (3)
1- The structural and functional unit of life is .
d) Organ system
2- ‘Suicide bag’ in a cell is
3- Kwashiorkor is caused due to deficiency of
Give the answer in one word.(4)
4- Who discovered vaccine?
5- What are disease causing organisms called?
6- Who proposed cell theory and when?
7- Which material is plant cell wall composed of?
Short answer questions. (8)
8- Where are proteins synthesised inside the cell?
9- Why is plasma membrane called a selectively permeable membrane?
10- State any two conditions essential for good health.
11- Name any two immunisation programmes available at the nearest health centre in your locality. Which of these diseases are a major problems in your area?
Short answer questions. 6
12- What are the different means by which infectious disease spread?
13- Differentiate between prokaryotic and eukaryotic cells.
Long answer questions(5)
14- Make a comparison and write down the ways in which plant cells are different from animal cells.