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प्रश्न
Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.
उत्तर
Two observations that may suggest that a chemical reaction has taken place are
(i) evolution of a gas and
(ii) change in temperature.
For example, zinc granules react with dilute sulphuric acid to evolve hydrogen gas, which is easily observed by the bubbles of hydrogen gas appearing around zinc granules. Also, the flask becomes hot, which shows heat is evolved during the reaction—that is, change in temperature.
Zn + H2SO4 → ZnSO4 + H2↑ + Heat
संबंधित प्रश्न
What is wrong with the following chemical equation?
Mg + O → MgO
Correct and balance it.
The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.
(a) What is metal M?
(b) What is solution S? Is it acidic or alkaline?
(c) What is gas G?
(d) Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.
(e) Is this reaction exothermic or endothermic?
Write the chemical equation for the following word equation and balance them.
Sodium reacts with water to form sodium hydroxide and hydrogen
Write the balanced chemical equation of the following reaction.
potassium dichromate + hydrochloric acid → Potassium chloride + chromium chloride + water + chlorine
Write word equation for the following molecular equation:
\[\ce{N2 + 3H2 ⇌[Fe - 450°C][200 atoms] 2NH3 + \triangle}\]
Word equation:
State why [+ Δ] indication is seen after NH3.
State what 200 atmospheres – indicates.
State the function of Fe in the above reaction.
Representation of the results of a chemical change – is a chemical equation.
For the equation: FeCl3 + 3NH4OH 3NH4Cl + Fe(OH)3 ↓
Answer the following:
Name the reactants and the products in the above equation.
Balance the following simple equation:
NO + O2 → NO2
CaCO3 + 2HCl[dil.] → CaCl2 + H2O + CO2 [g]
State the information provided by the above chemical equation.
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
3CuO + NH3 → 3Cu + 3H2O + N2
Write the skeleton equation for the following word equation and then balance them.
- Carbon + Oxygen → Carbon dioxide.
- Phosphorus + Chlorine → Phosphorus pentachloride.
- Sulphur + Oxygen → Sulphur dioxide.
- Magnesium + hydrogen → Magnesium + Hydrogen chloride chloride.
