CBSE Questions for Class 8 General Knowledge Basic Science Quiz 2 - MCQExams.com

Which one of the following statements about fossil human species is correct? 
  • Fossils of Homo neanderthalensis have been found recently in South America
  • Neanderthal man and Cro-Magnon man did . exist for sometime together
  • Austra/opithecus fossils have been found in Australia
  • Homo erectus was preceded by Homo habilis
Which of the following planet has less density ?
  • Uranus
  • Mars
  • Mercury
  • Venus
The angle of projection $${\theta}$$  for which range is equal to maximum height attained by projectile is 
  • $${tan ^{-1} 4}$$
  • $${tan^{-1} 5}$$
  • $${tan ^{-1} 4/5}$$
  • $${tan ^{-1} 5/4}$$
Example of omnivorous animals is ____________.
  • Sheep
  • Deer
  • Lion
  • Cockroach
Choose the odd one out.
  • Wheat
  • Rice
  • Sugar
  • Gram
In the shown figure mass of the pulley is m and radius 2R A light concentric spool of radius R is rigidly attached with the pulley Two blocks A and B having masses m & 4m respectively are attached with the pulley by means of light strings Lower surface of the block B is attached to a spring of stiffness k and block B rests on a smooth inclined plane inclined $$\displaystyle 30^{\circ}$$ with horizontal Other end of the spring is fixed to the ground Initially the blocks are held at a height such that spring is in relaxed position The block A is streatched a small distance and released The strings do not slip on the pulley and spool

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  • In equilibrium the extension in the spring is zero
  • In equilibrium the extension in the spring is 2mg/k
  • The time period of oscillation of block B is T = $$\displaystyle 2\pi \sqrt{\frac{10m}{k}}$$
  • The time period of oscillation of block B is T = $$\displaystyle 2\pi \sqrt{\frac{8m}{k}}$$
Recently ,a team of scientist have created world's first high definition 3D  model of a complete human brain .What is the name of this human brain?
  • 3D Brain
  • Amazing Brain
  • Big Brain
  • Intel Brain
World AIDS DAY is observed on 
  • Ist January
  • Ist April
  • Ist September
  • Ist December
Three particles A, Band C are thrown from the top of a tower with the same speed. A is thrown up, B is thrown down and C is horizontally. They hit the ground with speeds$${ V_{A}}$$ , $${V_{B}}$$  and $${V_{C}}$$ respectively
  • $${V_{A}= V_{B}= V_{C}}$$
  • $${V_{A}= V_{B}> V_{C}}$$
  • $${V_{A}> V_{B}>V_{C}}$$
  • $${V_{A}>V_{B}= V_{C}}$$
Which of the following is an example of Insectivorous plant _________.
  • Cuscuta
  • Rafflesia
  • Drosera
  • Tulsi
The correct angle of banking for a curved road of radius $$150 m$$ for a speed of $$90 {km}/{h}$$ of a four wheeler is
  • $$23$$
  • $$20$$
  • $$27$$
  • $$25$$
The moment of inertia of a thin spherical shell of mass M and radius R about a diameter is $$\displaystyle\frac{2}{3}MR^2$$. Its radius of gyration K about a tangent will be.
  • $$\sqrt{\displaystyle\frac{2}{3}}R$$
  • $$\displaystyle\frac{2}{3}R$$
  • $$\displaystyle\frac{5}{3}R$$
  • $$\sqrt{\displaystyle\frac{5}{3}}R$$
A sphereical solid ball of mass $$1$$kg and radius $$3$$cm is rotating about an axis passing through its centre with an angular velocity of $$50rad/s$$. The kinetic energy of rotation is.
  • $$4500J$$
  • $$90J$$
  • $$910J$$
  • $$0.45J$$
A body weighths $$200N$$ at the surface of earth. If it be placed in an artificial satellite revolving at height where acceleration due to gravity is half of that at earth's surface. It will weigh.
  • $$100N$$
  • $$200N$$
  • $$400N$$
  • Zero
The speed $$v$$ of a particle moving along a straight line is given by $$a+bv^2=x^2$$ (where $$x$$ is its distance from the origin). The acceleration of the particle is.
  • $$bx$$
  • $$\displaystyle\frac{x}{a}$$
  • $$\displaystyle\frac{x}{b}$$
  • $$\displaystyle\frac{x}{ab}$$
A simple pendulum is made by attaching a $$1$$kg bob to a $$5$$m long copper wire. Its period is T. Now, if $$1$$kg bob is replaced by $$10$$kg bob, the period of oscillation.
  • Remians T
  • Becomes greater than T
  • Becomes less than T
  • Any of above depends on locality
An electron moving with a variable linear velocity $$v$$ and $$B$$ will remain rotating in a circle of constant radius $$r$$ only when.
  • $$B$$ is held constant
  • $$v$4 is held constant
  • Both $$v$$ and $$B$$ are constant
  • None of the above
When the intermolecular distance decreases due to compressive force, there is.
  • Zero resultant force between molecules.
  • Replusive force between molecues.
  • Attractive force between molecules.
  • No force between molecules
The velocity constant of a reaction at $$290K$$ was found to be $$3.2\times {10}^{-3}$$. At $$300K$$ it will be
  • $$1.28\times {10}^{-2}$$
  • $$6.4\times {10}^{-3}$$
  • $$9.6\times {10}^{-3}$$
  • $$3.2\times {10}^{-4}$$
The X-ray tube is operated at $$50kV$$. The minimum wavelength produced is.
  • $$0.5\overset{o}{A}$$
  • $$0.75\overset{o}{A}$$
  • $$0.25\overset{o}{A}$$
  • $$1.0\overset{o}{A}$$
The length of a seconds pendulum is.
  • $$99.8$$cm
  • $$99$$cm
  • $$100$$cm
  • None of these
The length of a needle floasting on water is $$2.5$$cm. Calculate the added force(due to surface tension) required to pull the needle out of water. (Surface tension of water $$=7.2\times 10^{-2}N/m^2$$)
  • $$3.6\times 10^{-3}N$$
  • $$3.4\times 10^{-10}N$$
  • $$3.0\times 10^{-5}N$$
  • $$3.8\times 10^{-11}N$$
Two springs of force constant $$1000N/m$$ and $$2000N/m$$ are streched by same force. The ratio of their respective potential energies is.
  • $$2:1$$
  • $$1:2$$
  • $$4:1$$
  • $$1:4$$
A pendulum suspended from the ceiling of a train has a period $$T$$ when the train is at rest. When the train accelerates with a uniform acceleration $$a$$, the period of oscillation will.
  • Increase
  • Decrease
  • Remain unaffected
  • Become infinite
A man stands in a narrow, steep-sided valley. When he shouts he hears two echoes, one after $$1$$s and other after $$2$$s. If the velocity of osund in air is $$330m/s$$, the width of the valley is.
  • $$330m$$
  • $$495m$$
  • $$660m$$
  • $$990m$$
Which one of the following is the main cause of the ecological imbalance in India?
  • Deforestation
  • Desertification
  • Floods and famines
  • Rainfall variations
India is a party to the Ramsar Convention and has declared many areas as Ramsar Sites. Which of the following statements best describes as to how we should maintain these sites in the context of this convention?
  • Keep all the sites completely inaccessible to man so that they will not be exploited.
  • Conserve all the sites through ecosystem approach and permit tourism and recreation only.
  • Conserve all the sites through ecosystem approach for a period without any exploitation with specific criteria and specific period for each site, and then allow sustainable use of them by future generations.
  • Conserve all the sites through ecosystem approach and allow their simultaneous sustainable use.
Which relation is wrong? 
  • $$1cal=4.18J$$
  • $$1\mathring { A } ={ 10 }^{ -10 }m$$
  • $$1\mu ={ 10 }^{ -6 }m\quad $$
  • $$1\quad mile=1.12km$$
Which one of the following is the correct sequence about various levels of organization of Biosphere?
  • Ecosystem-Biosphere-Community - Population
  • Population - Organism - Ecosystem -Biosphere
  • Organism - Community - Population -Biosphere
  • Organism - Population - Ecosystem -Biosphere
Who proposed the term Ecosystem ____________.
  • A.G.Tensely
  • E.P. Odum
  • Carl Mobius
  • Earnst Haeckel
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