SCIENCE
41. A device used to change the resistance in an electric circuit is
A. ammeter B. rheostat C. galvanometer D. voltmeter
Ans: B. rheostat
Solution:
In an electric circuit, a device called rheostat is often used to change the resistance in the circuit.
42. In Fleming’s left hand rule middle finger indicates the direction of the
A. magnetic field B. electric current induced in conductor
C. electric current D. movement of the conductor
Ans: C. electric current
Solution:
Fleming’s left hand rule: The forefinger indicates the direction of the magnetic field; the middle finger indicates the direction of the current and the thumb represents the direction of the motion.
Ans: A. ‒2m and concave lens
Solution:
Power = 1/f
-0.5 = 1/f
f = -1/0.5
f = -2m
f = -200cm
since focal length is negative, lens is concave (diverging)
44. The nature and the size of the image formed when the object is kept between the principal focus ‘F1 ’ and optical centre ‘O’ of a convex lens is
A. virtual, erect and enlarged B. real, inverted and small size
C. virtual, inverted and small size D. real, inverted and enlarged
Ans: A. virtual, erect and enlarged
Solution:
Ans: A. 15Ω
Solution:
Given :
Potential Difference of heater = 60v
current I=4A
Resistance =R?
By Ohm's law :
V=IR
R=V/R
=60/4=15 ohms
Ans: C. operture
Solution:
diameter of the circular outline of a spherical lens is called aperture
Ans: B. absorbs more heat
Solution:
Ans: D. converts mechanical energy into electrical energy
Solution:
Ans: C. magnetic nature
Solution:
the resistance of a conductor depends on its length, thickness (i.e. its cross sectional area) and temperature of the conductor
50. D.C. generator works on the principle of
A. electromagnetic induction B. magnetic effect of electric current
C. heating effect of electric current D. chemical effect of electric current
Ans: A. electromagnetic induction
Solution:
A DC generator operates on the principle of Faraday's laws of electromagnetic induction. According to Faraday's law, whenever a conductor is placed in a fluctuating magnetic field (or when a conductor is moved in a magnetic field) an EMF is induced in the conductor.
51. ‘WATT’ is an SI unit of
A. electric current B. electric charge
C. electric potential difference D. electric power
Ans: D. electric power
Solution:
Ans: B. L
53. One of the properties of biogas
A. Its heating capacity is high B. Leaves residue like ash
C. It burns with smoke D. Its heating capacity is low
Ans: A. Its heating capacity is high
Solution:
Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen (anaerobically), primarily consisting of methane and carbon dioxide. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste.
- Biogas don't pollute the environment.
- Its heating capacity is high
- It is renewable source of energy.
- It reduces soil, water and air pollution.
- It produces organic manure as byproduct.
- As it is a low-cost method to produce energy, so it is economically friendly as well.
Ans: C. + 0.33
Solution:
u= -60 cm
v= 20 cm
Mafnification Formula :- M=v/u
M= -20cm/-60cm
M= 1/3
M=0.33
So, the correcet answer is option C +0.33..
55. The process used to convert metal carbonate ores into their oxides is :
A. roasting B. reduction C. electrolysis D. calcination
Ans: D. calcination
Solution:
A carbonate ore is converted into oxide by calcination whereas a sulphide ore is converted into oxide by roasting.
56. The correct group of saturated hydrocarbon
A. CH4 , C2 H4 , C3 H4 B. C2 H6 , C3 H8 , C4 H10
C. C2 H2 , C2 H6 , CH4 D. C2 H2 , C3 H6 , C4 H6
Ans: B. C2 H6 , C3 H8 , C4 H10
Solution:
Saturated Hydrocarbons: contain only carbon- carbon single bonds.
Unsaturated Hydrocarbons: contain carbon- carbon double or triple bonds
57. The atomic number of an element ‘X’ is 11 and the atomic number of ‘Y’ is 17. Then the type of bond formed between these two elements
A. hydrogen bond B. covalent bond
C. ionic bond D. metallic bond
Ans: C. ionic bond
Solution:
The electronic configuration of element X(Z = 11) is Na = 2, 8, 1
The electronic configuration of element Y(Z = 17) is Cl = 2, 8, 7
The bond form will be of ionic nature. atom of X is Na will transfer 1 electron each to atoms of Y is Cl.
The formula of the compound is : NaCl
58. As the pH value of a solution decreases
A. number of OH‒ ions increases
B. number of H+ ions increases
C. number of H+ ions decreases
D. equal number of OH‒ and H+ ions
Ans: B. number of H+ ions increases
Solution:
pH is the scale used to determine the concentration of hydrogen ions in solution. The scale ranges from 0−14 with 7 being the neutral value. Less than 7 is acidic and more than 7 is basic. Hence, the pH value increases with decrease in hydrogen ion concentration
59. The functional group present in the carbon compound is
A. aldehyde B. alcohol C. ketone D. carboxylic acid
Ans: D. carboxylic acid
Solution:
Functional groups are the atoms or group of atoms attached to a hydrocarbon chain which changes the property of parent hydroarbon chain .
Ans: A. 4
Solution:
In the modern Periodic table this element belongs to group 2 and period 7.
This can be identified by its atomic no. and its electronic configuration.
As the electronic configuration of 20 will be (2,8,8,2) its valency is 2 and thus it belongs to group 2 and the no. of shells present are 4 n therefore it belongs to period 4.
As the elements placed towards the right-side or present in the s-block are metals.
therefore this element is a metal.
61. The number of single bonds present in the structure of a cyclohexane molecule
A. 12 B. 18 C. 24 D. 6
Ans: B. 18
Solution:
Ans: C. increases
Solution:
On moving down the group, from top to bottom, the atomic size increases. This is because with increase in the atomic number, extra shells of electrons are added.
Ans: A. Zn > Fe > Cu
Solution:
Ans: D. Hydrogen
Solution:
When dilute sulphuric acid is poured on zinc granules, then zinc being more reactive than hydrogen displaces it from the acid and forms zinc sulphate and hydrogen gas.
Zn + H2SO4 → ZnSO4 + H2
Hydrogen is a combustible gas and burns with a popping sound. This can be observed when a match stick which is burnt is bought ear to the test tube.
65. NaOH + HCl → NaCl + H2 O. This chemical reaction is an example of
A. neutralization reaction B. substitution reaction
C. addition reaction D. combustion reaction
Ans: A. neutralization reaction
Solution:
The neutralization reaction is the one in which an acid reacts with an equimolar amount of base to give salt and water. In neutralization reactions, the H+ of the acid combines with OH− ions of the base to form water and other reactants form the specific salt. The neutralization reaction has a pH of 7.
66. The molecular formula of benzene is
A. C5 H12 B. C6 H12 C. C6 H6 D. C6 H10
Ans: C. C6 H6
Solution:
Ans: B. Transpiration
Solution:
Ans: D. Pulmonary veins → Left atrium → Left ventricle
Solution:
Ans: C. Thyroxin
Solution:
Testosterone is the male sex hormone that is made in the testicles. During puberty (in the teen years), testosterone helps boys develop male features like body and facial hair, deeper voice, and muscle strength.
The adrenal glands are endocrine glands that are responsible for producing important hormones required for bodily functions. Adrenaline is also known as a fight hormone.
The hormone that regulates carbohydrate, protein and fat metabolism in the human body is Thyroxin
Insulin reduces the blood glucose levels immediately by increasing the transport of glucose in adipose tissue, skeletal muscle cells and liver cells. Insulin stimulates the uptake of the glucose in these cells from the blood.
70. The mismatched pair among the following
A. Adrenaline → Pituitary gland
B. Testosterone → Testes
C. Insulin → Pancreas
D. Thyroxin → Thyroid gland
Ans: A. Adrenaline → Pituitary gland
Solution:
The adrenal glands are located at the top of each kidney. They are responsible for producing many hormones, including aldosterone, cortisol, adrenaline, and noradrenaline. Adrenal glands are controlled by another gland called the pituitary gland.
Ans: D. cerebellum
Solution:
The pons is the primary structure of the brain stem present between the midbrain and medulla oblongata. The main functions of the pons include: Controlling sleep cycles.
The cerebrum is responsible for thinking, intelligence, consciousness and memory.
Hypothalamus main function is maintaining the body’s internal balance- homeostasis.
Cerebellum is the part of human brain responsible for precision of voluntary actions and maintaining the posture and balance of the body
72. A pathogen that causes gonorrhoea and syphilis transmitted through sexual contact :
A. Protozoa B. Bacteria C. Virus D. Fungus
Ans: B. Bacteria
Solution:
Gonorrhea is caused by the bacterium Neisseria gonorrhoeae. The gonorrhea bacteria are most often passed from one person to another during sexual contact,
syphilis is caused by the bacterium Treponema pallidum. The syphilis bacteria are most often passed from one person to another during sexual contact.
73. The correct sequence found in the process of sexual reproduction in flower is
A. pollination, fertilization, embryo, seed
B. seed, embryo, fertilization, pollination
C. embryo, seed, pollination, fertilization
D. pollination, fertilization, seed, embryo
Ans: A. pollination, fertilization, embryo, seed
74. The part of the plant seed that grows and develops into root on germination
A. Cotyledon B. Endosperm C. Radicle D. Seed Coat
Ans: C. Radicle
Solution:
The radicle is the first part of a seedling (a growing plant embryo) to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil (the shoot emerges from the plumule).
Ans: D. Round and yellow
Solution:
Ans: B. acquired traits
Solution:
The experiences of an individual during his/her lifetime cannot be passed on to its progeny because these experiences are an example of acquired traits. These are the changes in the somatic cells which do not take part in reproduction and hence, cannot give rise to inheritance.
77. Analogous organs have
A. Same structure and same function
B. Same structure and different functions
C. Different structures and same function
D. Different structures and different functions
Ans: C. Different structures and same function
Solution:
Ans: B. Ultra violet - radiations
Solution:
In the stratosphere, ozone is created primarily by ultraviolet radiation. When high-energy ultraviolet rays strike ordinary oxygen molecules (O2), they split the molecule into two single oxygen atoms, known as atomic oxygen. A freed oxygen atom then combines with another oxygen molecule to form a molecule of ozone.
Ans: D. repurpose
Solution:
Reduce the consumption of various resources wherever
possible. For example- we can reduce the consumption of electricity by
switching off lights and other appliances when they are not required.
Recycle- There are many items which can be recycled again
and again. Recycling is another way of reducing the demand for natural
resources. For example- by recycling paper, we reduce the demand for wood and
thus, help in saving the forest.
Reuse- Many items can be reused, many times. For example,
the old newspaper can be used for packing many items. We can use one side
printed sheets for our rough work at home/work.
Repurpose- This means when a product can no more be used for
the original purpose, think carefully and use it for some other useful purpose.
For example, cracked crockery, or cups with broken handles can be used to grow
small plants and as feeding vessels for birds.
Refuse- This means to say No to things people offer you that
you don’t need. Refuse to buy products that can harm you and the environment,
say no to single-use plastic carry bags.
80. The watershed management
A. Increases production and income of watershed community
B. Increases droughts and floods
C. Decreases the biodiversity of downstream reservoirs
D. Increases deforestation
Ans: Increases production and income of watershed community
Solution:
Watershed is defined as the area of land where all the water drains into a central point, like rivers, lakes or streams.
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