Advertisements
Advertisements
Question
What do you observe when :
an iron nail is kept in tap water for few days
Solution
We observe reddish brown coating on the nail called rust (entirely new substance) is chemical change.
APPEARS IN
RELATED QUESTIONS
How do the following help in bringing about a chemical change?
heat.
Complete and balance the following chemical equations:
Fe `"SO"_4` + NaOH `→`
(aq.) (aq.)
FILL IN THE BLANK
Positively charged ions are called ........
TRUE \ FALSE
A precipitation reaction takes place only in a solution.
How is precipitate formation in a chemical reaction indicated?
Define electrolysis.
Differentiate between in Chemical reaction and chemical equation.
State four conditions necessary for a chemical reaction to take place.
Explain the following reaction with one suitable example of Combination reactions .
Name the type of chemical reaction shown by the following equation:
Fe + CuSO4 → FeSO4 + Cu
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)
An ______ is drawn in between the reactants and products while writing the equation for a chemical reaction.
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)
Oxygen is a ______ in respiration.
Match the pairs.
| a. | Photosynthesis | i. | Tendency to lose electrons |
| b. | Water | ii. | Reactant in combustion process |
| c. | Sodium chloride | iii. | Chemical change |
| d. | Dissolution of salt in water | iv. | Covalent bond |
| e. | Carbon | v. | Ionic bond |
| f. | Fluorine | vi. | Physical change |
| g. | Magnesium | vii. | Tendency to form anion |
State the conditions necessary for a chemical change or reaction.
Give an example of the following chemical change.
Two solids combine to form a liquid
Complete the following table and write your observations.
|
Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
|
|
Shake the gas with red litmus solution |
||||
|
Shake the gas with blue litmus solution |
||||
|
Apply a burning splint to a gas |
What do you observe when HCI is passed through a silver nitrate solution.
Distinguish by heating the following in dry test tubs.
Copper Sulphate and copper carbonate
Distinguish by dilute sulphuric acid.
Sodium Sulphite and sodium carbonate?
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
Select the correct answer for the following options:
The black residue obtained on heating copper carbonate.
Give a word equation for the following reaction.
An exothermic reaction where both the reactants are gases, one of which is oxygen.
State the following reaction represent oxidation or reduction.
\[\ce{Cu++->Cu}\]
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Calcium hydroxide.
Burning of paper is a ______ change.
Classify the following as physical or chemical properties
Most metal oxides form alkalis on interacting with water.
How would you show that the settling of curd is a chemical change?
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
