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MODEL PAPER 7 — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceMODEL PAPER 73 Marks
Question
i. Predict the reaction, if any, between
a. zinc and silver nitrate solution,
b. magnesium and iron (II) chloride solution,
c. copper and magnesium sulphate solution.
Write the equations, with its physical form symbols, for the reaction.
ii. A lump of element X can be cut by a knife. During its reaction with water, X floats and melts. What is X? Explain.
✓

Answer

i. a. Zinc is more reactive than silver. It will displace silver from silver nitrate solution and will form zinc nitrate in the
solution.
$Zn ( s )+2 AgNO _3( aq ) \rightarrow Zn \left( NO _3\right)_2( aq )+2 Ag ( s )$
b. Magnesium is more reactive than iron. It will displace iron from iron (II) chloride solution and will form magnesium
chloride in the solution.
$Mg ( s )+ FeCl _2( aq ) \rightarrow MgCl _2( aq )+ Fe ( s )$
c. Copper is less reactive than magnesium. It will not displace magnesium from magnesium sulphate solution and, hence, no
reaction will take place.
$Cu ( s )+ MgSO _4( aq ) \rightarrow$ No reaction
ii. X is potassium (K). Potassium is a soft metal that's why it can be cut with a knife and it is lighter than water that's why it floats
on the surface of water and the heat produced melts the potassium.

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