Displcement reaction. metal added to solutions containing metal that is less reactive would have visible reaction while less reactive metal will have no visible reaction. Eg, if copper is added to Mgcl2 andZnCl2, there will be no visible reaction. If Mg is added to CuCl2, blue solution will fade to form colourless solution and a reddish brown ppt of Cu will be formed.
Answer: condenstation.
Justification:
The polymerization by condensation is a well know chemical reaction in which two monomers ("small" molecules), each with (at least) two functional groups, combine and relase water as by-product. Actually, even if the by-product released is not water, yet the reaction is called condenstation, since the mechanism is basically the same.
An example of such reaction is the manufacturing of nylon 6,6, which is produced from adipic acid and 1,6-diamine hexane:
HOOC - [CH₂]₄ - COOH + nH₂N - [CH₂]₆ - NH₂ → - nylon - + nH₂O
I omitted the formula of nylon because it is large, and that is not the core of the question but the fact the kind of reaction: two molecules combine to form is a larger molecule, and water is released
We have to know the molarity of solution obtained when 5.71 g of Na₂CO₃.10 H₂O is dissolved in water and made up to 250 cm³ solution.
The molarity of solution obtained when 5.71 g of sodium carbonate-10-water (Na₂CO₃.10 H₂O) is dissolved in water and made up to 250.0 cm^3 solutionis: (A) 0.08 mol dm⁻³
The molarit y of solution means the number of moles of solute present in one litre of solution. Here solute is Na₂CO₃.10 H₂O and solvent is water. Volume of solution is 250 cm³.
Molar mass of Na₂CO₃.10 H₂O is 286 grams which means mass of one mole of Na₂CO₃.10 H₂O is 286 grams.
5.71 grams of Na₂CO₃.10 H₂O is equal to 
= 0.0199 moles of Na₂CO₃.10 H₂O. So, 0.0199 moles of Na₂CO₃.10 H₂O present in 250 cm³ volume of solution.
Hence, number of moles of Na₂CO₃.10 H₂O present in one litre (equal to 1000 cm³) of solution is 
= 0.0796 moles. So, the molarity of the solution is 0.0796 mol/dm³ ≅ 0.08 mol/dm³
Answer:
it's urine option ( C ) .
