Question 1 :
Two drops of dilute sulphuric acid were added to $1g$ of copper sulphate and then small amount of hot water was added to dissolve it (step I). On cooling beautiful blue coloured crystals got separated (step II).Step(I) and step (II) are:<br>
Question 2 :
Weight of crucible+weight of magnesium wire=x (before heating)<br/>Weight of crucible+ weight product magnesium oxide=y (after heating)<br/>Which of the following option is correct?
Question 4 :
The surface area of the reacting particle can be increased by:
Question 6 :
Write 'true' or 'false' for the given statement. Rewrite the false statement correctly:                  Dissolving of solute in a solvent and rusting of iron are both physical changes.
Question 9 :
Rusting is a special term, given to the corrosion of which metal?
Question 10 :
Which of them is not the characteristics of a physical change?
Question 13 :
The change which is permanent and cannot be measured by just reversing the condition is known as:
Question 14 : <span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small"><p class="wysiwyg-text-align-left">In hydrogen evolution type of corrosion with respect to hydrogen electrode which of the following is correct ?</p>
Question 15 :
Reactions that take place under the influence of electricity are called:
Question 16 :
Changes in which one or more new substances are formed are called _______ changes.
Question 17 :
The metal $(M)$ forms an oxide, ${M}_{2}{O}_{3}$. The formula of its nitride will be
Question 19 :
Paheli's mother made concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates a-<br/>
Question 22 :
In an explosion, the nuclear energy is released in the form of:
Question 23 :
A chemical reaction in which energy is liberated is called :
Question 26 :
For a chemical change to occur the particles should be in:
Question 28 : <p>Which of the following cause a substance to change into an entirely new substance with a new chemical formula?</p>
Question 29 :
When magnesium ribbon burns in air, it forms white ash. The chemical name of white ash is:
Question 32 :
Which of the following is a physical change?<br/>a) Hammering of a red hot iron rod to make a flat sheet.<br/>b) Formation of ice by cooling of water.<br/>c) Rising up of water vapors from sea to make clouds.<br/>d) Heating of charcoal in air to high temperature till it begins to flow.
Question 34 :
Physical changes like boiling do not make new materials and are easily reversed e.g. by cooling, which causes ________.
Question 37 : <p class="wysiwyg-text-align-left"><span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small">Iron rod is dipped in concentrated $ HNO_{3} $. After sometime it is dipped into a $ AgNO_{3} $ solution. $ Ag $ was not displaced by iron because:</p>
Question 44 :
Melting of butter is a physical change. State whether the statement is true or false
Question 47 : <span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small"><p class="wysiwyg-text-align-left">The technique of protecting a metal from corrosion by connecting it to a second metal (that is more easily oxidised) is called:</p>
Question 48 :
Change in which one or more new substances are formed is known as a:
Question 49 :
The energy required to break the bonds and elevate the reaction is called as:
Question 50 :
The reaction given below is a:<br/>${Copper \ sulphate \left ( soln \right ) + Iron\rightarrow Iron \ sulphate \left ( soln \right )+Copper}$<br/>
