List of top Science Questions

Match the items in Column I with one or more items of Column II.
 

Column IColumn II
Upper jawhave fins on the body.
Fishhas an outer skeleton.
Ribscan fly in the air.
Snailis an immovable joint.
Cockroachprotect the heart.
-shows very slow movement.
-have a streamlined body
What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?
Explain the following giving examples.
(a) Saturated solution
(b) Pure substance
(c) Colloid
(d) Suspension
Fill in the blanks:
  1. Fossil fuels are ___, ___ and ___.
  2. Process of separation of different constituents from petroleum is called ___.
  3. Least polluting fuel for vehicle is ___.
State two ways to prevent the rusting of iron.

What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Name the source from which litmus solution is obtained. What is the use of this solution?
What are the advantages of using CNG and LPG as fuels?

Select the correct word from the following list and fill in the blanks.
float, water, crop, nutrients, preparation

  1. The same kind of plants grown and cultivated on a large scale at a place is called ____.
  2. The first step before growing crops is ____ of the soil.
  3. Damaged seeds would ____ on top of water.
  4. For growing a crop, sufficient sunlight and ____ and ____ from the soil are essential.
Explain how deforestation leads to reduced rainfall.
Why does the sky appear dark instead of blue to an astronaut?
Fill in the blanks:
  1. Most liquids that conduct electricity are solutions of ___, ___ and __.0.
  2. The passage of an electric current through a solution causes ___ effects.
  3. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ___ terminal of the battery.
  4. The process of depositing a layer of any desired metal on another material by means of electricity is called ___.
In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut trees for such projects? Discuss and prepare a brief report.

Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).

Substance Dissolved

Temperature in K

283

293

313

333

353

 

Solubility

Potassium nitrate213262106167
Sodium chloride3636363737
Potassium chloride 3535404654
Ammonium chloride2437415566

 

(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K? 
(b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain. 
(c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature? 
(d) What is the effect of change of temperature on the solubility of a salt?

Which of the statements about the reaction below are incorrect?
\(\text{ 2PbO(s) + C(s) → 2Pb(s) + C}O_2\text{(g)}\)
(a) Lead is getting reduced. 
(b) Carbon dioxide is getting oxidized. 
(c) Carbon is getting oxidized. 
(d) Lead oxide is getting reduced.
State which of the following situations are possible and give an example for each of these: 
  1. an object with a constant acceleration but with zero velocity 
  2. an object moving with an acceleration but with uniform speed. 
  3. an object moving in a certain direction with an acceleration in the perpendicular direction.
In an experiment \(4.5\) kg of a fuel was completely burnt. The heat produced was measured to be \(180,000\) kJ. Calculate the calorific value of the fuel.
How does phototropism occur in plants?
Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.
Show the shape of the distance-time graph for the motion in the following cases:
(i) A car moving with a constant speed.
(ii) A car parked on a side road.
An object of mass 100 kg is accelerated uniformly from a velocity of 5 m s–1 to 8 m s–1 in 6 s. Calculate the initial and final momentum of the object. Also, find the magnitude of the force exerted on the object.

Which separation techniques will you apply for the separation of the following?

(a) Sodium chloride from its solution in water
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride
(c) Small pieces of metal in the engine oil of a car
(d) Different pigments from an extract of flower petals
(e) Butter from curd
(f) Oil from water
(g) Tea leaves from tea
(h) Iron pins from sand
(i) Wheat grains from husk
(j) Fine mud particles suspended in water

Compounds such as alcohols and glucose also contain hydrogen but are not categorized as acids. Describe an Activity to prove it.

Define valency by taking examples of silicon and oxygen.