Answer :Option A) The lattice energy increases as cations get smaller, as shown by LiF and KF.
Explanation : It is observed that lattice energy is mostly influenced by two main factors of an ionic solid which are;
i) The charge on the ions - As the charge of the ions increases, the lattice energy is observed to increase too.
and
ii) The radius, or size, of the ions- As the size of the ions increases, the lattice energy decreases with it.
So, here in this question the second reason is clearly observed. Hence, it is self-explained that the size of the cations are decreased in the ionic solids the lattice energy increases.
The number of electrons in a completely filled second shell of an atom will be 8.
The basic number of ordinary components that make up a chemical element is just an atom.
As per Bohr's atomic model, electrons orbit or shell surrounding the nucleus in a precise circular path.
It is known that by the electronic configuration atoms posses 2,8,18,32.
Hence, there are 8 electron will be found in second shell of the atom.
The number of electrons in a completely filled second shell of an atom will be 8.
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Answer:
C. The enthalpy of a reaction is the sum of the enthalpies of intermediate reactions.
Explanation:
The heat of any reaction ΔH∘f for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction.
They are both carried from place to place by particles.
B.
They are both kinds of mechanical energy.
C.
They both need a medium to travel through.
D.
They both have a wavelength and a frequency.
Explanation
D.
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(2) melting of copper
(3) condensation of ethanol vapor
(4) sublimation of iodine
Answer:
The correct answer is option 3.
Explanation:
Condensationof ethanol vapors is an exothermic process. This is because particles in gaseous has highest energy . Some of this energy gets released when these particles or ethanol vapors condenses into a liquid state where they have less amount of energy in comparison to gaseous state.
As we know that exothermic reaction are those reaction in which heat is released into the surroundings.
Where as the other options are example of an endothermic reaction.where heat is absorbed from the surroundings.
Hence, the correct answer is option 3.
B. CO2
C. H2O
D. CH4
Answer : The correct option is, (C)
Explanation :
Formula used:
where,
V = number of valence electrons present in central atom
N = number of monovalent atoms bonded to central atom
C = charge of cation
A = charge of anion
First we have to determine the hybridization of the following molecules.
(a)
This is diatomic molecule and diatomic molecules always form linear shape.
(b)
The number of electrons is 2 that means the hybridization will be and the electronic geometry of the molecule will be linear.
(c)
The number of electrons is 4 that means the hybridization will be and the electronic geometry of the molecule will be tetrahedral.
But as there are two atoms around the central oxygen atom, the third and fourth position will be occupied by lone pair of electrons. The repulsion between lone and bond pair of electrons is more and hence the molecular geometry will be bent.
(d)
The number of electrons is 4 that means the hybridization will be and the electronic geometry of the molecule will be tetrahedral.
Hence, the molecule has bent structure will be,
(2) distillation
(3) electrolysis
(4) filtration
Answer : Option 3) Electrolysis.
Explanation : In the process of electrolysis, decomposition of the chemical is done by passing the electric current from the liquid or the solution containing ions in it. This is the process where compound is broken into ions namely, cations and anions.
Rest all options does not involves chemical decomposition of the compound.
Chromatography is a technique where rates of solute and solvent are compared in a medium where the solute components move at different rates and the separation is obtained.
Distillation simply purifies the liquid or solution by heating or cooling process.
Filtration just involves removal of impurities by using a more porous material device to get purified compound.
Answer:
The correct answer is option (3).
Explanation:
Electrolysis is defined as chemical process in which decomposition is carried out by passing an electricity in a solution containing ions. For example: electrical decomposition of water gives oxygen gas and hydrogen gas.
where as chromatography, distillation and filtration are the separation techniques used to separate the compounds from the mixtures.
Hence, the correct answer is option (3).