Advertisements
Advertisements
प्रश्न
Fill in the blank
A new substance is always formed in a _______ change.
उत्तर
A new substance is always formed in a chemical change.
APPEARS IN
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
pressure.
Fill in the blank.
The formation of gas bubbles in a liquid during a reaction is called ......................
What do you observe when Iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
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
TRUE \ FALSE
Evaporation of water is a physical change. True or false ?
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
Fill in the blank
A new substance is formed in a _______ change.
Differentiate between in Chemical reaction and chemical equation.
Write true or false :
When potassium iodide solution is added to lead acetate solution a red precipitate is formed.
Copper carbonate when heated, it turns :
A solution of a substance ‘X’ is used for white washing write the reaction of the substance ‘X’ named in (a) above with water.
Give an example of a reaction where the following are involved:
Close contact
Give an example of the following chemical change.
Two gases combine to form white solid
Give a chemical test to distinguish between the following gases.
H2 and CO2
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium dichromate.
Distinguish by dilute sulphuric acid.
Copper and magnesium?
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.
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 coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
Complete the table given below.
| Heat on iodine crystals | Colour of vapours evolved |
Complete the table given below.
| Heat on Zinc nitrate | Colour of residue |
State the following reaction represent oxidation or reduction.
\[\ce{Ag->Ag+}\]
Explain the term chemical reaction with special reference to reactants and products.
______ gas causes tears in our eyes while cutting onions.
Explain the following statement: Digestion is a chemical change.
Rusting of Iron: undesirable change:: Dead plants turn into manure: ______.
Burning of paper is the best example of ______ change.
Iron benches kept in lawns and gardens get____________. It is a _________ change because a new _________ is formed.
When milk is mixed with coffee decoction, the colour of milk and decoction changes due to ______.
