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प्रश्न
Which among the following are physical or chemical change?
Evaporation of petrol
उत्तर
Physical
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संबंधित प्रश्न
In the following reaction between lead sulphide and hydrogen peroxide:
PbS (s) + 4H2O2(aq) → PbSO4(s) + 4H2O(1)
(a) which substance is reduced?
(b) Which substance is oxidised?
Fill in the following blanks with suitable words:
The addition of hydrogen to a substance is called ........ whereas removal of hydrogen is called .......
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.
Compare hydrogen with alkali metals on the basis of:
Oxide formation
Complete and balance the following equation:
Fe + H2O →___________+____________
Which among the following are physical or chemical change?
Burning of Liquefied Petroleum Gas (LPG)
A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
- Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
- Name the black substance formed and give its chemical formula.
What happens when zinc granules are treated with dilute solution of H2SO4, HCl, HNO3, NaCl and NaOH Also write the chemical equations if reaction oçcurs.
Identify the following reactions as oxidation/reduction/redox reaction
2Mg +O2 → 2MgO
Define oxidation number.
