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Class 10 · Science · Expert
→Which substance is the white powder formed when a magnesium ribbon burns in air?
Class 10 · Science · Expert
→What is the main purpose of rubbing magnesium ribbon with sandpaper before burning it?
Class 10 · Science · Expert
→In the balanced equation \(2Mg + O_2 \rightarrow 2MgO\), what is the total number of oxygen atoms on the product side?
Class 10 · Science · Easy
→How many hydrogen atoms are present in two water molecules?
Class 10 · Science · Expert
→Why is it incorrect to change the subscripts in a chemical formula while balancing a chemical equation?
Class 10 · Science · Easy
→What is the main reason for keeping atoms of every element equal on both sides of a balanced equation?
Class 10 · Science · Expert
→During a reaction in an open container, if a produced gas escapes, why can the measured mass of the container and its remaining contents appear to decrease?
Class 10 · Science · Expert
→When calcium carbonate is heated in an intact closed container, it decomposes into calcium oxide and carbon dioxide. If the carbon dioxide does not escape, what can be concluded about the total mass of the container and its contents before and after the reaction?
Class 10 · Science · Hard
→An iron nail is kept in a blue copper sulphate solution for some time. A reddish-brown coating forms on the nail and the solution turns light green. Which statement about this change is correct?
Class 10 · Science · Hard
→Which arrangement is most suitable for reliably testing the law of conservation of mass?
Class 10 · Science · Hard
→Which of the following reactions is a decomposition reaction but not a thermal decomposition reaction?
Class 10 · Science · Hard
→Which of the following is a decomposition reaction but not an electrolytic decomposition reaction?
Class 10 · Science · Hard
→Which of the following is a chemical change but not a precipitation reaction?
Class 10 · Science · Hard
→What is the correct difference between the symbols (aq) and (l) in a chemical equation?
Class 10 · Science · Hard
→A student writes the rusting reaction as \(Fe + H_2O \to Fe_2O_3 + H_2\). What is the most fundamental error in this statement?
Class 10 · Science · Hard
→If gas evolves in an unknown reaction but colour does not change what is the most careful conclusion?
Class 10 · Science · Hard
→Why should a chemical reaction not be confirmed carelessly from colour change alone?
Class 10 · Science · Hard
→Which statement identifies a reaction as a displacement reaction?
Class 10 · Science · Hard
→How is chewing food different from digesting it?
Class 10 · Science · Hard
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