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science qa1

1. The Symbol of SI Unit for “Amount of Substance” is
a) mol
b) mole
c) molecular
d) Cd
a. molHere the keyword is ‘Symbol’. The Symbol of SI Unit for Amount of Substance is mol whereas the SI Unit of Amount of Substance is mole.

2. The instrument used to measure the altitude of an object is
a. Ammeter
b. Altimeter
c. Anemometer
d. Audiometer
b. Altimeter
Altimeter is mostly used in aircrafts. Ammeter measures the strength of Electric current. Anemometer measures force and velocity of wind and its directions. Audiometer measures the intensity of Sound.

3. The Wood Furniture are coated with which chemical to protect from Termite destruction
a. Copper sulphate
b. Sodium Nitrate
c. Plaster of Paris
d. Zinc chloride
d. Zinc chloride
Copper sulphate is used as insecticide and in electric cells. Sodium Nitrate is a fertilizer. Plaster of Paris is mainly used in Statues and in surgery purposes.
I. This is the largest group of the Plant Kingdom
II. The body of the plants in this group are not differentiated into root, stem and leaves.
Choose the correct statement
a. I only           b. II Only
c. I and II        d. None
c. I and II

5. Cellular Respiration in plants takes place as
a. Plant uses Oxygen and Produces Carbon dioxide
b. Plant uses Carbon dioxide and Produces Oxygen
c. Plant uses both Oxygen and Carbon dioxide and produces water
d. None of the above
a. Plant uses Oxygen and Produces Carbon dioxide.
It is very important to note that, Photosynthesis is different and Respiration is different. For the process of Photosynthesis, plants intake Carbon dioxide from the atmosphere and uses it with water in presence of Sun Light and the products of Photosynthesis are Glucose, Water and Oxygen.
Normally Respiration denotes the movement of Oxygen into the body of organism (inhale) and release of Carbon dioxide.
Cellular Respiration is the process of reaction of Oxygen with Glucose in the cells of the organisms to produce Energy, Water and Carbon dioxide (this Carbon dioxide is released out).
Hence for respiration, the plants too need Oxygen. Usually, plants uses the Oxygen produced from Photosynthesis process for its respiration instead of getting from atmosphere. The excess Oxygen after using for respiration is given out to the atmosphere. This is generally said as Plants intake Carbon dioxide and gives out Oxygen.

6. According to Buoyant force, When object is immersed in a fluid (liquid or gas), it experiences an apparent loss of weight which is equal to the
a) Weight of the Object itself
b) Weight of the Fluid
c) Combined weight of the Object and Fluid
d) None of the above
b. Weight of the fluid
(Std 9 – Liquids)
The Buoyant force is also called as Archimedes’ principle as it was said by him. According to it, When a body is immersed in a fluid, (liquid or gas) it experiences an apparent loss of weight which is equal to the weight of the fluid displaced. The reason for the apparent loss of weight we know is the buoyant force.

7. The Electrical cell converts,
a. Mechanical Energy into Electrical Energy
b. Electrical Energy into Mechanical Energy
c. Chemical Energy into Electrical Energy
d. All the above.
c. Chemical Energy into Electrical Energy.
An electric cell has two different metal plates called electrodes kept inside a chemical called electrolyte. Due to chemical reaction, one plate develops a positive charge and the other plate develops a negative charge and produces electric current.

8. In Agricultural practices, the method of Irrigation in which the water is allowed to enter the field through channels made between the two rows of crops is known as
a) Basin Irrigation
b) Drip Irrigation
c) Sprinkler Irrigation
d) Furrow Irrigation
d. Furrow Irrigation
(Std 8 – Crop production and management)
The Furrow irrigation method is used in crops like Sugarcane, Banana, Paddy.
Furrow Irrigation
Basin irrigation: In this method the field is just filled with water. (e.g Paddy)
Sprinkler irrigation: This irrigation is used where the soil cannot retain water for a long time. Here the water is sprinkled by sprinklers. e.g. Lawn
Drip irrigation: In this irrigation the water falls drop by drop directly at the position of the roots, so it is called drip irrigation. It is the best method to save water. It helps to irrigate grapes, banana, brinjal, etc.

9. The openings in the Leaves, through which the air and water comes out is called as
a. Petiole
b. Stipules
c. Stomata
d. Vein
c. Stomata

10. The Chemical reaction in which the Heat is evolved as an byproduct is known as
a. Exothermic Reaction
b. Endothermic Reaction
c. Redox Reaction
d. Combustion Reaction
a. Exothermic Reaction
(Std 10 – Chemical Reaction)
The chemical reactions which take place with the evolution of heat energy are called exothermic reactions.
N2 + 3H2 ? 2NH3 + Heat
The chemical reactions which take place with the absorption of heat energy are called endothermic reactions.
2NH+ Heat ? N2 + 3H2
The Chemical Reaction in which both the Oxidation and Reduction takes place is called as Redox reactions.

11. The middle layer in the structure of Skin Tissue is
a) Hypodermis
b) Epidermis
c) Dermis
d) Follicle
c. Dermis
(Std 9 – Human Body Organ System)
The skin is like an envelope and its complex structure is divided into three layers of tissues: 1.Epidermis 2.Dermis 3.Hypodermis
Epidermis is the upper layer of the skin. The outermost layer consists of flat, thin and scale – like dead cells. It is separated from the dermis by the basement membrane.
The dermis is the middle layer. It is thick but elastic. The dermis consists of nerves, blood vessels, hair follicles, sweat glands and sebaceous glands (oil glands). Sweat glands separate sweat from the blood.
It is the innermost layer of the skin. It is thick and contains large amounts of adipose tissue.

12. Consider the following properties
I. Its main source is combustion of fuels
II. It reacts with hemoglobin in human blood and reduces the affinity of Oxygen with hemoglobin and this may lead to death.
Which Gas has the above properties?
a) Carbon monoxide
b) Carbon dioxide
c) Nitrogen oxides
d) Sulphur dioxide
a. Carbon monoxide
(Std 8 – Air, Water and Soil Pollution)
Carbon dioxide leads to Global warming. Nitrogen oxides from automobile exhaust cause acid rain. Sulphur dioxide causes irritation in the eyes, lung cancer and asthma.

13. The World Health Organisation defines adolescence as the period of life between
a. 9 and 18 years of age
b. 11 and 18 years of age
c. 11 and 19 years of age
d. 13 and 19 years of age

c. 11 and 19 years of age
(Std 8 – Reaching the age of adolescence)