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Class 10 · Science · Hard
→If heat is written along with the products in a chemical equation and light is also emitted during the reaction, what is the nature of the reaction?
Class 10 · Science · Medium
→If a container becomes very cold during a reaction, what is the most suitable explanation of the energy change?
Class 10 · Science · Hard
→What common effect do antioxidants and airtight packaging have?
Class 10 · Science · Hard
→During electrolysis of acidified water, 15 mL of oxygen is collected at the anode. A student says that 15 mL of hydrogen will also be produced at the cathode because water contains both H and O. What is the correct correction to the student's statement?
Class 10 · Science · Medium
→Why will rancidity increase quickly in ghee kept in a warm open place?
Class 10 · Science · Easy
→What is the main chemical cause of rancidity in oily food?
Class 10 · Science · Hard
→Why does exposed iron remain protected from rusting for some time even when the zinc coating in galvanisation is scratched?
Class 10 · Science · Hard
→A student states that the reaction \(\mathrm{AgNO_3(aq)+NaCl(aq)\rightarrow AgCl(s)+NaNO_3(aq)}\) is both a precipitation reaction and a redox reaction. What is the correct evaluation of this statement?
Class 10 · Science · Hard
→Which of the following reactions is not an oxidation-reduction (redox) reaction?
Class 10 · Science · Medium
→Which of the following equations represents a double displacement reaction that forms a precipitate?
Class 10 · Science · Easy
→Which pair shows oxidation first and reduction second?
Class 10 · Science · Medium
→In a chemical reaction, oxygen is removed from substance A and the same oxygen is added to substance B. What is the most appropriate classification of this reaction?
Class 10 · Science · Hard
→A student writes the reaction for heating potassium chlorate as \(KClO_3 \xrightarrow{\Delta,\,MnO_2} KCl + O_2\). What is the correct evaluation of this equation?
Class 10 · Science · Easy
→If copper oxide becomes copper in the reaction with hydrogen, what change has occurred?
Class 10 · Science · Hard
→Why is the reaction between barium chloride and sodium sulphate classified as both a double-displacement and a precipitation reaction?
Class 10 · Science · Easy
→When a precipitation reaction occurs on mixing two aqueous solutions, what is its clearest visible evidence?
Class 10 · Science · Hard
→When two aqueous solutions are mixed, a white precipitate of barium sulphate forms and sodium chloride remains in solution. Which pair of reactants is correct?
Class 10 · Science · Hard
→Zinc displaces copper from copper sulphate solution, but copper does not displace zinc from zinc sulphate solution. What is the correct conclusion?
Class 10 · Science · Medium
→Metal A displaces metal B from a solution of its salt, and metal B displaces metal C from a solution of its salt. What is the correct order of reactivity of the metals?
Class 10 · Science · Hard
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