Advertisements
Advertisements
Question
Define; catalyst.
Solution
Catalyst: A catalyst is a substance that either increases or decreases the rate of a chemical reaction without itself undergoing any chemical change during the reaction.
APPEARS IN
RELATED QUESTIONS
Changes in which new substances are formed are called ______ changes.
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Complete and balance the following chemical equations:
`"H"_2"S"` + `"CI"_2` `→`
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
MATCH THE COLUMNS
| 1 . `H_2` + `CI_2` `→` 2HCI | a. displacement reaction |
| 2. `2FeCI_3`+ `H_2` `→` `2FeCI_2` +2HCI` | b. addition of an electronegative redical |
| 3. Fe + `CuSO_4` `→``FeSO_4` +Cu` | c. removal of an electronegative redical |
| 4. `2H_2O` +`4NO_2`+`O_2` `→` `4HNO_3` | d.reduction by adding hydrogen |
| 5. 3Fe +`3CI_2` `→` `2FeCI_3` | e.electrolysis of water |
| 6. `FeCI_3`+ 3NaOH `→``Fe(OH)_3``↓`+NaCI | F.double decomposition,precipitation reaction |
| 7.`2H_2O` `→` `2H_2``↑`+`O_2` | e. combination or synthesis reaction |
TRUE \ FALSE
Evaporation of water is a physical change. True or false ?
What are the characteristics of a chemical reaction ? A chemical reaction is characterised by an irreversible change in which a new substance is formed.
How is a strong electrolyte different from a weak electrolyte?
Fill in the blank:
The basic conditions necessary for a chemical reaction is _______
Name the type of chemical reaction shown by the following equation:
2Mg + O2 → 2MgO
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 white particles of baking soda disappear when put in lemon juice. This means that it is a ______ change.
Give reason for the following:
Blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
What is a chemical change? Give two examples of chemical change?
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
State the original colour of the following substance and colour of residue obtained after heating.
Lead nitrate
Distinguish by heating the following in dry test tubs.
Zinc carbonate, Copper carbonate and lead carbonate.
Write your observation and a balanced equation in the case of the following substances being heated.
Copper carbonate.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Thermal decomposition of mercury [II] oxide.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A white solid which evolves two colourless gases which on cooling combine and condense on the cooler parts of the test tube.
Select the correct answer from the options given below:
State the gaseous product formed, when
An active metal reacts with dilute sulphuric acid.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
________ is a chemical substance which alters the speed of a chemical reaction.
When an aqueous solution of potassium chloride is added to an aqueous solution of silver nitrate, a white precipitate is formed. Give the chemical equation of this reaction.
State whether the following statements are true or false:
When a candle burns, both physical and chemical changes take place.
Vanaspati is obtained from vegetable oils by the addition of ______ to the oils.
______ is the chemical name of limestone.
What is the difference between reactants and products?
