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प्रश्न
Give a word equation for the following reaction.
A compound which on heating shows – colour change from brown to yellow.
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उत्तर
Lead dioxide →Lead oxide + Oxygen
2Pb02 → 2PbO + 02 (l)
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
catalyst .
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
What are chemical reactions?
Write true or false :
When potassium iodide solution is added to lead acetate solution a red precipitate is formed.
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.
Explain by writing a word equation.
Bubbles are seen on adding lemon juice to baking soda.
State the conditions necessary for a chemical change or reaction.
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
Multiple choice:
A reaction of a type: AB + CD → AD + CD, involves
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
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 – Addition of dilute hydrochloric acid to silver nitrate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc nitrate to nitrogen dioxide
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
Burning of paper is a ______ change.
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.
Chemists identify gypsum as a natural indicator.
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
Give an example of a chemical reaction for the following situation:
A change in colour is observed
Beating an egg to make a cake is a ______.
Acid rain is a result of ______.
