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Which of the following alkenes will react fastest with under catalytic hydrogenation conditions?
The reactivity order towards H2 is
cis > iso > trans i.e in option A the alkene is cis.
The heat of hydrogenation of 1-hexene is 126 . When a second double bond is introduced in the molecule, the heat of hydrogenation of the resulting compound is 230 . The resulting compound (diene) is
1,3 -hexadiene is a conjugated diene, hence it is more stable than the first compound. The heat of hydrogenation decreases as the stability of the molecule increases. The stability of 13 hexadiene is more than that of a compound which contain two double bonds.
Heat of hydrogenation of benzene is 51 kcal/mol and its resonance energy is 36 kcal/mol. Then the heats of hydrogenation of cyclohexadiene and cyclohexene per mole respectively are
Total energy to break 3 bond in benzene is 87 [51+36].
So to break one bond i.e. in cyclohexaene is 87/3= 29kcal/mol.
And to break 2 bond i.e.in cyclohexadiene is 29*2= 58 kcal/mole.
gas is liberated at cathode and anode both by electrolysis of the following aq. solution except in :
At the cathode (C), water is reduced to hydroxide and hydrogen gas. The net process is the electrolysis of an aqueous solution of NaCl into industrially
Electrolysis of aqueous sodium chloride yields hydrogen and chlorine, with aqueous sodium. Chlorine gas bubbles out of the melt above the anode.
“10 volume” means :
H2O2 is the special concentration terms.10 volume of H2O2 means that 1ml of H2O2 gives 10 ml of O2.
For example, if it was mentioned 30 volume of H2O2, then its means that 1ml of H2O2 gives 30ml of O2.
(heavy water) and differ in following except
Chemical properties won't change in case of isotopes. Therefore answer is D.
The work done by the system in a cyclic process involving one mole of an ideal monoatomic gas is 50 KJ/cycle, The heat absorbed by the system per cycle is
According to the first law of thermodynamics,
∆Q=∆U+∆W and for a cyclic process, change in internal energy(∆U) is zero. Hence ∆Q=∆W where ∆Q is the heat absorbed and ∆W is the work done. Therefore heat absorbed is 50 kJ
Which of the following is not correct ?
It should be equal to T, not (-T)
Enthalpy of Rhombic sulphur of C is
Rhombic sulphur is the standard state of sulphur or in its pure state.And in standard state it is taken as zero.
Which of the following is not a state function ?
A state function is the property of the system whose value depends only on the initial and final state of the system and is independent of the path.Heat (q) and work (W) are not state functions being path dependent.
The pH of 10-7 M HCl is
Without calculation one can also say that the answer is a because acid has a ph value less than 7.
1c.c. of 0.1N HCl is added to 99 c.c. aqueous solution of sodium chloride.The pH of the resulting solution will be
Normality volume = (0.1) (0.001)
Normality volume = 0.0001 L
Volume of solution = Volume of NaCl + Volume of HCL
Volume of solution = 1 + 0.001
Volume of solution = 1.001 L
Since NaCl is a salt and is neutral so it does not effect pH of a solution.
Normality of HCL in a resulting solution = 0.0001 / 1.001
Normality of HCL in a resulting solution = 0.0001 N
pH = - log [H⁺]
pH = - log (0.0001)
pH = 4
which shows that the pH of the resulting solution is 4
0.2 molar aqueous solution of is found to be 90% ionized at 298 K.The pH of the solution is
Lets calculate the pOH first,
Since 1 mol Ba(OH)2 gives 2 moles of OH- 0.2 moles will give 0.4 mol OH-
However its 90% ionised and hence [OH-] = 0.36 M
So pOH = -log [0.36]
pH = 14-0.443
If the maximum concentration of in water is 0.01M at 298K, its maximum concentration in 0.1M NaCl will be
Concentrations of the ions:
The dissociation reaction for PbCl2 in water is write as,
The maximum concentration of PbCl2 in water is 0.01 M
We can find concentration of the ions using the stoichiometry from the above reaction.
The concentration of Pb²⁺ ion is 0.01 M and concentration of Cl⁻ ion is 2×0.01=0.02M.
The solubility product of PbCl2 can be written as,
Let us insert in the concentrations of Pb and Cl.
Concentration of Pb2+ using common ion effect:
WhenPbCl2 is dissolved in 1MNaCl, there is a common ion Cl−. This decreases the solubility of PbCl2 due to the common ion effect.
The concentration of Cl− in 0.1MNaCl is 0.1. Let us plug in this value to find the new concentration of Pb2+ ion.
When equal volumes of the following solution are mixed, precipitation of AgCl will occur only with
AgCl is precipitated only when [Ag+][Cl-] > Ksp
On mixing equal volumes of two solutions, concentration becomes halved.
Ammonium hydrogen sulphide is contained in a closed vessel at 313 K when total pressure at equilibrium is found to be 0.8 atm. The value of for the reaction
Ammonium hydrogen sulphide is contained in a closed vessel at 313K when total pressure at equilibrium is found to be 0.8 atm.
Total pressure PNH3+PH2S=P+P=2P
But total pressure is 0.8 atm.
The value of the equilibrium constant for the reaction,is Kp=PNH3×PH2S
Which of the following hydrocarbons has the highest melting point?
Melting point order is para > ortho > meta on basis of symmetry . So option b is correct.
Reaction of ethene with in gives
When alkenes react with Br2 in presence of CCl4 it gives vicinnyl dibromides (1 2 dibromide )
The major product obtained when isobutane is treated with chlorine in the presence of light is
The major product is tert butyl chloride as firstly isobutylchloride is formed but then hydride shift takes place due to which chlorine shift to more stable tertiary carbocation and hence the product is tert butyl chloride.
SO2 can act as both oxidizing as well as reducing agent since it has +4 oxidation state which is exactly between
its highest oxidation state +6 and lowest oxidation state +2 ,
Thus it can change its oxidation number either from +4 to-2(reduction) and +4 to+6 (oxidation)
Which one of the following leads to a redox reaction
Redox reactions are characterized by the transfer of electrons between chemical species, most often with one species undergoing oxidation while another species undergoes reduction.
It is an example of a redox reaction.
Hence, option C is correct.
The compound contains atoms X,Y,Z. The oxidation number of X is 2, Y is 5 and Z is –2, a possible formula of the compound is
The net charge on the compound should be zero. Or the sum of oxidation states = 0.
Given: oxidation number of X is +2, Y is +5 and Z is -2.
A compound contains atoms X, Y and Z . The oxidation number of X is +2 , Y is +5 and Z is -2.
The possible formula of the compound is X3(YZ4)2.
How many allotropic forms of carbon are there ?
Carbon has three well known allotropes which are graphite, daimond and buck minster fullerene.
Graphite has a layered structure. The distance between the layers is
Since the layers are only weakly attracted to each other, they can easily slide past one another. This is why graphite is used in pencil lead. The distance between layers is 335 pm. Carbon atoms in diamond are covalently bonded and are arranged in a three-dimensional tetrahedral structure.
Coal gas is a mixture of
Coal gas contains a variety of calorific gases including hydrogen, carbon monoxide, methane, ethylene and volatile hydrocarbons together with small quantities of non-calorific gases such as carbon dioxide and nitrogen.
Formic acid (HCOOH) on heating with concentrated gives
H2SO4 + HCOOH → CO + H2SO4•H2O.
Sulfuric acid react with formic acid to produce carbon monoxide and hydrate sulfuric acid.
Which of the following gases is used for the purification of nickel ?
CO is the gas used for purification of nickel and this process is called Mond process.
The most stable oxidation state of boron is
The elments of the boron family adopts oxidation states +3 or +1. The +3 oxidation states are favorable except for the heavier elements, such as Tl, which prefer the +1 oxidation state due to its stability; this is known as the inert pair effect.
Which of the following products are formed when boron is fused with NaOH ?
Boron reacts with fused sodium hydroxide to form sodium borate and hydrogen.
B + 6NaOH →→ 2Na3BO3 + 3H2
reacts with to produce
B2H6 + 6Cl2 → 2BCl3 + 6HCl
Diborane react with chlorine to produce boron(III) chloride and hydrogen chloride...
In the Serepeck process, the bauxite ore is treated with
Serpeck process is a method of purification of Bauxite ore containing silica (SiO2) as the main impurity.
The reaction involved are-
Anhydrous produces fumes in the air because of
Anhydrous aluminium chloride is hydrolised partly with the moisture in the atmosphere to give HCl gas. This HCl gets combine to moisture in air giving white fumes. So white fumes appear by hydrolysis.
A real gas obeying van der Waals equation will resemble an ideal gas if
According to van der Waals equation for 1 mole of a real gas
If a and b are small, a/V2 and b can be neglected as compared to P and V and the equation reduces to PV=RT. Hence, a real gas will resemble an ideal gas when constants a and b are small.
In which of the following pairs do the molecules (gaseous) have the same root-mean-square speed
RMS speed = √(3RT/M) where, T is temperature, R is universal gas constant and M is molecular mass of gas
Here molecular mass is same for N2 (14x2=28) and CO (12+16=28) so rms speed will also b same for them as rest all is constant
The pressure at the base of a column of liquid of length l and held at an angle to the vertical is
Pressure at the base of a liquid column =hdg
Here h=height of the column
d=density of liquid
g=acceleration due to gravity
since the column is inclined at an angle θ the vertical height=l cosθ
so option (d) is correct