Answer: Bohr postulated that electronic energy levels are quantized. Secondly, a photon of light of a particular frequency is emitted when electrons move from a higher to a lower energy levels.
Explanation:
The Bohr model of the atom is the immediate predecessor of the wave mechanical model of the atom. The wave mechanical model refined the Bohr's model by treating the electron as a wave having a wave function psi. The wave function describes the identity of the electron. From Heisenberg uncertainty principle, the position of a particle cannot be accurately and precisely measured. Hence the wave mechanical model added that electrons are not localized in orbits according to Bohr's model but the integral of psi squared dx gives the probability of finding the electron within a given space.
Answer: The correct option is 2.
Explanation: Heat flow is defined as the transfer of energy from hotter object to cooler object when two objects are kept together at different temperatures. As the energy remains conserved, so the heat flow will take place until the equilibrium is attained.
In the above asked question, Object A is at 40° C and Object B is at 80° C.
Object B is at higher temperature, so the heat flow will take place from Object B to Object A.
Hence, the correct option is 2.
Explanation:
Distinguish chemical substances from mixtures
Key Points
Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components.
A chemical substance is composed of one type of atom or molecule.
A mixture is composed of different types of atoms or molecules that are not chemically bonded.
A heterogeneous mixture is a mixture of two or more chemical substances where the various components can be visually distinguished.
A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.
Various separation techniques exist in order to separate matter, including include distillation, filtration, evaporation and chromatography. Matter can be in the same phase or in two different phases for this separation to take place.
Terms
substanceA form of matter that has constant chemical composition and characteristic properties. It is composed of one type of atom or molecule.
elementA chemical substance that is made up of a particular kind of atom and cannot be broken down or transformed by a chemical reaction.
mixtureSomething that consists of diverse, non-bonded elements or molecules.
Answer:
An Element is a substance made up of only one type of atom as like gold, copper, oxygen, etc.
Copper sulphate with molecular formula 
, the elements are copper, sulphur and oxygen. It is formed by combination of 
cation and 
anion.
Copper sulphide with molecular formula 
, the elements are copper and sulphur. It is formed by combination of cation and 
anion.
Here we have to get the 
of the reaction at 520 K temperature.
The of the reaction is 1.705 atm
We know the relation between and 
is 
, where = The equilibrium constant of the reaction in terms of partial pressure, = The equilibrium constant of the reaction in terms of concentration and N = number of moles of gaseous products - Number of moles of gaseous reactants.
Now in this reaction, PCl₃ + Cl₂ ⇄ PCl₅
Thus number of moles of gaseous product is 1, and number of moles of gaseous reactants are 2. Thus N = |1 - 2| = 1 mole
The given value of is 4.0×10⁻²
The molar gas constant, R = 0.082 L. Atm. mol⁻¹. K⁻¹ and temperature, T = 520 K.
On plugging the values in the equation we get,
Or, = 1.705 atm
Thus, the of the reaction is 1.705 atm
