The deficiency of which of the following leads to dental caries ?
Carotene in Indian cow's milk causes?
Plants that grow in saline water are known as :
In the context of genetic code, consider the following statements:
A. Although an amino acid may have two or more codons, each codon specifies only one amino acid.
B. Amino acid codons are identical in human beings, tobacco plants and viruses.
Which of the statements given above is/are correct?
In protein synthesis in E. coli. When each amino acid is attached to a specific to RNA at the expense of ATP energy, the ion of which one of the following elements is used?
Sodium vapour lamps are preferred over incandescent lamp because of
In an ordinary dry cell, the electrolyte is
Which of the following pairs of materials serves as electrodes in chargeable batteries commonly used in devices such as torch lights, electric shavers etc. ?
The mixed oxide fuel is used for which of the following?
Acid rain is caused by the pollution of environment by
The clouds float in the atmosphere because of their
End product in fermentation is
Chemical that is used in photography
Which gas is used in domestic refrigerators?
Match sticks are made of
When a particle or a body moves with a uniform speed v on a circular path of radius r, then it is acted upon by a force mv2/r which is always directed
Explanation: When a particle or a body moves with a uniform speed v on a circular path of radius r, then it is acted upon by a force mv2/r which is always directed towards the centre of the circle. This force is called centripetal force
The value of escape velocity depends upon
Explanation: The value of escape velocity does not depend upon the mass of the projected body; instead it depends on the mass and radius of the planet from which it is being projected. The value of escape velocity does not depend on the angle and direction of projection
Consider the following about Fuse Wire and choose the incorrect statement:
It is made up of a material with high melting point
Explantion: Fuse Wire is used in a circuit to control the maximum current flowing in a circuit. It is a thin wire having high resistance and is made up of a material with low melting point.
When a lawn roller is pulled by applying a force along the handle at an acute angle, work done by the applied force is
Explanation: When a lawn roller is pulled by applying a force along the handle at an acute angle, work done by applied force is (+) ve.
Which mirrors are commonly used as rear-view (wing) mirrors in vehicles:
Explanation: Convex mirrors are commonly used as rear-view (wing) mirrors in vehicles. These mirrors are fitted on the sides of the vehicle, enabling the driver to see traffic behind him/her to facilitate safe driving. Convex mirrors are preferred because they always give an erect, though diminished, image. Also, they have a wider field of view as they are curved outwards. Thus, convex mirrors enable the driver to view much large area than would be possible with a plane mirror.
An air bubble in water behaves as a
Consider the following statements:
Choose the correct option:
Explanation: If the lens is immersed in a medium having refractive index equal to that of the lens, then
The lens becomes invisible.
The lens behaves as a plane glass plate.
The focal length becomes infinite.
What is true about Sound waves?
Explanation: Sound travels in the form of waves. Sound waves are longitudinal waves. Thus, they do not exhibit polarisation.
Which among the following is true?
Explanation: Amplitude – the maximum displacement on one side of mean position of a particle of medium, is called the amplitude of the wave.
Time period -the time taken by a particle of the medium to complete its one vibration in called the time period of the wave.
Frequency -the number of vibrations made by a particle is called the frequency of the wave.
Wave velocity - the distance travelled by a wave in one second is travelled by a wave in one second is called wave velocity.
Wavelength - the distance travelled by a wave in one time period of a medium is called its wavelength.
Tension in the string of simple pendulum is
Explanation: Tension in the string of simple pendulum is always perpendicular to the displacement of the bob, hence it is zero.