Chemistry:2011:CBSE:[All India]:Set-III

The excess energy which must be supplied to the reactants to undergo chemical reactions is called activation energy.

The phenomenon of reversal of the direction of osmosis by the application of a pressure larger than the osmotic pressure on the solution side is known as reverse osmosis. In this case, the pure solvent flows out of the solution through a semi permeable membrane.

If the ore or the gangue can be attracted by the magnetic field, then the ore can be concentrated by the process of magnetic separation.

The IUPAC name of CH₂=CHCH₂Br is 3-bromopropene.

There is a gradual decrease in atomic and ionic radii of lanthanoids (from lanthanum to lutetium) with an increase in atomic number. This is known as ‘lanthanoid contraction’.

When dehydration of ethanol is carried out at 443 K, ethene is formed. The following chemical reaction takes place.

The structure of 4-chloropentan-2-one is as follows:

Ethylamine and aniline can be distinguished from each other by the azo-dye test. An orange coloured dye is obtained when aniline (an aromatic amine) reacts with HNO₂ (NaNO₂ + dil.HCl) at 0-5°C, followed by a reaction with the alkaline solution of 2-naphthol. The dye is usually yellow, red or orange in colour. Ethylamine (an aliphatic amine) gives a brisk effervescence (due to the evolution of N₂ gas) under similar conditions.

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In a simple cubic lattice, the particles are located only at the corners of the cube and touch each other along the edge.
              

By knowing the density of an unknown metal and the dimension of its unit cell, the atomic mass of the metal can be determined.
Let ‘a’ be the edge length of a unit cell of a crystal, ‘d’ be the density of the metal, ‘m’ be the mass of each metal atom and ‘Z’ be the number of atoms in the unit cell.