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Question
Write true or false .
A black residue is formed when sugar is heated .
Options
True
False
Solution
True
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MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction is a chemical reaction in which there is
- removal of hydrogen
- removal of oxygen
- addition of oxygen
- none of these
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The new substances formed during a chemical reaction are called the ..................
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Distillation is a method of obtaining pure ............. from a solution.
What are biocatalysts ?
State four conditions necessary for chemical reactions to take place.
| Reactants | Products | Type of chemical reaction |
| BaCl2(aq) + ZnSO4(aq) | H2CO3(aq) | Displacement |
| 2AgCl(s) | FeSO4(aq) + Cu(s) | Combination |
| CuSO4(aq) + Fe(s) | BaSO4↓ + ZnCl2(aq) | Decomposition |
| H2O(l) + CO2(g) | 2Ag(s) + Cl2(g) | Double displacement |
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
The spoiling of food is a chemical change which is recognized from the generation of certain ______ due to it.
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
The conversion of ferrous sulphate to ferric sulphate is ______ reaction.
Give reason for the following:
Molybdenum is used in the manufacture of ammonia.
When hydrogen burns in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical change involved in the two cases.
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
Name: A greenish-yellow gas.
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
Select the correct answer for the following options:
The gas obtained when potassium chlorate is heated in the presence of a catalyst.
Complete the table given below.
| Heat on copper carbonate | Test for gas evolved |
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
Give a suitable example with an equation to show the representation of a chemical reaction.
Give a balanced equation for the conversion of an ammonium salt to a basic gas.
What kind of a change is associated with decaying of a plants?
______ gas causes tears in our eyes while cutting onions.
Burning of paper is a ______ change.
_____ is the basic material to manufacture urea.
Silver metal can displace hydrogen gas from nitric acid.
The water we drink is a combination of hydrogen and oxygen.
What is the use of indicator?
Classify each of the following, as a physical or a chemical change. Give reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change the colour of black tea by adding lemon juice to it.
(e) Churning of milk cream to get butter.
Which of the following is a chemical change?
Give an example where heat, light, and sound are produced during a chemical change.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
What is thermochemical reactions?
