Recent questions tagged class11

Kjeldahl's method cannot be used for estimation of nitrogen in $(i)\; C_6H_5NO_2 ;\; (ii)\;Pyridine; \;(iii)\;C_6H_5 - N = N -C_6H_5 ;\;(iv)\;C_6H_5NHCOCH_3 $

asked Feb 28, 2014 by meena.p

1 answer

The half life of radioactive radon is 3.8 days . The time , at end of which $\;\large\frac{1}{20}^{th}\;$ of radon sample will remain undecayed is

asked Feb 27, 2014 by yamini.v

1 answer

Two coins eash weighing 10 g are heated to 473 K and dropped into two identical vessels A and B, each containing 500 g of water at 298 K. The coin dropped in vessel A is made up of aluminium and the coin dropped into vessel B is amde up of silver. The rise in temperature of water in container

asked Feb 27, 2014 by mosymeow_1

1 answer

At $298\; K, 0.1\; mol$ of methane is burnt in a bomb calorimeter such that $\Delta V=0$. The heat so produced is taken up by a large amount of water so that $\Delta T$ is very small.

asked Feb 27, 2014 by mosymeow_1

1 answer

A $1.0\; g$ sample of substance A at $100^\circ C$ is added to $100\; mL$ of $H_2O$ at $25^\circ C$. Using separate $100\; mL$ portions of $H_2O$, the procedure is repeated with substance $B$ and then with substance $C$. How will the final temperatures of the water compare?

asked Feb 27, 2014 by mosymeow_1

1 answer

The amount of heat evloved when 500 $cm^3$ 0.1 M HCl is mixed with 200 $cm^3$ of 0.2 M NaOH is

asked Feb 27, 2014 by mosymeow_1

1 answer

$H_2O(g) + C(s) \rightarrow CO(g) + H_2(g)$ ; $\Delta H = 131$ kJ. $CO(g) + \frac{1}{2} O_2(g) \rightarrow CO_2(g)$ ; $\Delta H = -282$ kJ. $H_2(g) + \frac{1}{2} O_2(g) \rightarrow H_2O(g)$ ; $\Delta H = -242$ kJ. $C(s) + O_2(g) \rightarrow CO_2(g)$ ; $\Delta H = X $ kJ. Based on the above thermochemical equations find the value of X.

asked Feb 27, 2014 by mosymeow_1

1 answer

10 moles of an ideal gas expands into vacuum. The work done is

asked Feb 27, 2014 by mosymeow_1

2 answers

The source of energy in a cellular reaction is

asked Feb 27, 2014 by mosymeow_1

2 answers

The heat liberated when $1.89\; g$ of benzoic acid is burnt in a bomb calorimeter at $25^\circ C$ increases the temperature of $18.94\; kg$ of water by $0.632^\circ C$. If the specific heat of water at $25^\circ C$ is $0.998 \;cal/g$ deg, the value of the heat of combustion of benzoic acid is

asked Feb 27, 2014 by mosymeow_1

1 answer

What is the P-P bond energy in kJ/mol, if the heat of atomisation of $PH_3(g)$ and $P_2H_4(g)$ are 954 kJ/mol and 1485 kJ/mol, respectively?

asked Feb 27, 2014 by mosymeow_1

1 answer

Let the activation energies of two reactions be $E_1$ and $E_2$ where $E_1>E_2$. If temperature of the system is increased from $T_1$ to $T_2$, the rate constant of the reactions changes from $k_1$ to $k_1'$ in the first reaction and from $k_2$ to $k_2'$ in the second reaction. Which of the following expression is correct?

asked Feb 27, 2014 by mosymeow_1

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Which one of the following equation is true? (Given, $\delta E = T\delta S -P\delta V$ and $H=E+PV$)

asked Feb 27, 2014 by mosymeow_1

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The reaction $A \leftrightharpoons B$; $\Delta H = +24\; kJ/mol$. For the reaction $B\leftrightharpoons C$; $\Delta H=-18$ kJ/mol. The decreasing order of enthalpy of $A, B$ and $C$ follow the order

asked Feb 27, 2014 by mosymeow_1

1 answer

The enthalpy of neutralisation of oxalic acid by strong base is 25.4 kcal/mol. The enthalpy of neutralisation of strong acid and strong base is -13.7 kcal/equil. The enthalpy of dissociation of $H_2C_2O_4 \leftrightharpoons 2H^+ + C_2O_4^{2-}$ is

asked Feb 27, 2014 by mosymeow_1

1 answer

Cooking is fast in a pressure cooker because

asked Feb 27, 2014 by mosymeow_1

2 answers

To raise the temperature of 4.48 litres of an ideal gas at STP by $15^\circ C$ it requires 12.0 calories. The $C_P$ of the gas is

asked Feb 27, 2014 by mosymeow_1

1 answer

How many calories are required to heat 40 grams of argon from $40-100^\circ C$ at constant volume? (R = 2 cal/mol K)

asked Feb 27, 2014 by mosymeow_1

1 answer

$\Delta G^\circ$ for a reaction is 46.06 kcal/mol, $K_P$ for the reaction at 300 K is

asked Feb 27, 2014 by mosymeow_1

1 answer

Enthalpy =

asked Feb 27, 2014 by mosymeow_1

2 answers

Given, the enthalpy of combustion of glucose is 3000 kJ/mol. How much of glucose one has to consume to walk a distance of 5 km, provided 150 kJ of energy is needed for muscular work to walk a distance of 1 km and only 30 % energy is available for muscular work?

asked Feb 27, 2014 by mosymeow_1

1 answer

When 0.1 mole of a gas absorbs 41.75 J of heat, the rise in temperature occurs equal to $20 ^\circ C$. The gas must be

asked Feb 27, 2014 by mosymeow_1

1 answer

Enthalpy of formation of (C=C) and (C-C) in $C_2H_4$ is -590 kJ/mol and -331 kJ/mol, respectively. What is the enthalpy change when ethylene polymerises to form polythene?

asked Feb 27, 2014 by mosymeow_1

1 answer

At 273 K the enthalpy of a certain reaction is -20.75 kJ. If heat capacities of the reactants and products are the same, then what will be the enthalpy of the same reaction at 373 K?

asked Feb 27, 2014 by mosymeow_1

1 answer

$CO(g) + \frac{1}{2} O _2 \longrightarrow CO_2$, $\Delta H$ and $\Delta S$ for the reaction are $-283\; KJ$ and $-87\; JK^{-1}$. It was intended to carry out this reaction at $1000, 1500, 3000$ and $3500\; K$. At which of these temperatures would this reaction be thermodynamically spontaneous?

asked Feb 27, 2014 by mosymeow_1

1 answer

The molecules that will have dipole moments are : (i) 2,2 Dimethyl propane (ii) trans-2-pentene (iii) cis - 3 - Hexene (d) 2,2,3,3 -Tetramethyl butane

asked Feb 27, 2014 by meena.p

1 answer

Some equations are given below. Which of the following processes does not correctly represent the first law of thermodynamics ?

asked Feb 27, 2014 by mosymeow_1

1 answer

To 100 $cm^3$ water at 298 K, 0.06 mole of $KNO_3$ is added. The enthalpy of $KNO_3$(aq) solution is 35.8 kJ $mol^{-1}$. What will be the temperature of the solution, after the solute is dissolved?

asked Feb 27, 2014 by mosymeow_1

1 answer

Study the given diagram. 3 moles of gas is put through a series of thermodynamic changes as shown graphically in a cyclic process. The processes A $\rightarrow$ B, B $\rightarrow$ C and C $\rightarrow$ A respectively are

asked Feb 27, 2014 by mosymeow_1

1 answer

The displacement $y$ of a wave travelling in the $x$ - direction is $y = 10^{-4} \sin(600t – 2x + \large\frac{\pi}{3})m$, where, $x$ is in $m$ and $t$ is in $s$. The speed of the wave motion in $m/s$ is

asked Feb 27, 2014 by thanvigandhi_1

1 answer

When a carbon atom is linked to four different groups it is said to be chiral carbon atom. when alpha hydrogen atom of an alkane is replaced by a functional group we get corresponding compound.An optically active hydrocarbon $(A) C_6H_{10}$ on catalytic reduction gives optically inactive hydrocarbon . structure of $(A )$ is

asked Feb 27, 2014 by meena.p

1 answer

When a carbon atom is linked to four different groups it is said to be chiral carbon atom. when alpha hydrogen atom of an alkane is replaced by a functional group we get corresponding compound. IUPAC name for lowest molecular mas optically active alkene is

asked Feb 27, 2014 by meena.p

1 answer

When a carbon atom is linked to four different groups it is said to be chiral carbon atom. when alpha hydrogen atom of an alkane is replaced by a functional group we get corresponding compound. Lowest molecular mass optically active ketone contians ____ carbon atoms?

asked Feb 27, 2014 by meena.p

1 answer

When a carbon atom is linked to four different groups it is said to be chiral carbon atom. when alpha hydrogen atom of an alkane is replaced by a functional group we get corresponding compound. How many isomeric alkenes on catalytic reduction gives 3- methylhexane ?

asked Feb 27, 2014 by meena.p

1 answer

When a carbon atom is linked to four different groups it is said to be chiral carbon atom. when alpha hydrogen atom of an alkane is replaced by a functional group we get corresponding compound. How many C- atoms are present in lowest molecular mass optically active alkane?

asked Feb 27, 2014 by meena.p

1 answer

Optical and isomers are compounds which contain the same number and kinds of atoms, and bonds (ie the connectivity between atoms is the same), and different spatial arrangements of the atoms, but which have non-super imposable mirror images. Each non-super imposable mirror image structure is called an enantiomer. Optical isomers get their name because the plane – polarized light that is passed through a sample of a pure enantiomers is rotated. The planeis rotated in the opposite direction but with the same magnitude when plane- polarized light is passed through a pure sample containing the other enantiomer of a pair. A solution of one enantiomer rotates the plane of polrisation in a clockwise direction. This enantiomer is known as the (+) form. A solution of the other enantiomer rotales the plane of polarisation in an anti-clockwise direction. This enantiomer is known as (-) form.

asked Feb 27, 2014 by meena.p

1 answer

Optical and isomers are compounds which contain the same number and kinds of atoms, and bonds (ie the connectivity between atoms is the same), and different spatial arrangements of the atoms, but which have non-super imposable mirror images. Each non-super imposable mirror image structure is called an enantiomer. Optical isomers get their name because the plane – polarized light that is passed through a sample of a pure enantiomers is rotated. The planeis rotated in the opposite direction but with the same magnitude when plane- polarized light is passed through a pure sample containing the other enantiomer of a pair. A solution of one enantiomer rotates the plane of polrisation in a clockwise direction. This enantiomer is known as the (+) form. A solution of the other enantiomer rotales the plane of polarisation in an anti-clockwise direction. This enantiomer is known as (-) form.

asked Feb 27, 2014 by meena.p

1 answer

Optical and isomers are compounds which contain the same number and kinds of atoms, and bonds (ie the connectivity between atoms is the same), and different spatial arrangements of the atoms, but which have non-super imposable mirror images. Each non-super imposable mirror image structure is called an enantiomer. Optical isomers get their name because the plane – polarized light that is passed through a sample of a pure enantiomers is rotated. The planeis rotated in the opposite direction but with the same magnitude when plane- polarized light is passed through a pure sample containing the other enantiomer of a pair. A solution of one enantiomer rotates the plane of polrisation in a clockwise direction. This enantiomer is known as the (+) form. A solution of the other enantiomer rotales the plane of polarisation in an anti-clockwise direction. This enantiomer is known as (-) form.

asked Feb 27, 2014 by meena.p

1 answer

Find the sum to $n$ terms of the sequence $8,88,888,.............$

asked Feb 27, 2014 by rvidyagovindarajan_1

1 answer

If the $4^{th},10^{th}\:\;and\:\:16^{th}$ terms of a G.P. are $x,y\:\;and\:\:z$ respectively. Prove that $x,y,z$ are in G.P.

asked Feb 27, 2014 by rvidyagovindarajan_1

1 answer

Find the G.P. the sum of whose first two terms is $-4$ and the $5^{th}$ term is $4$ times the $3^{rd}$ term.

asked Feb 27, 2014 by rvidyagovindarajan_1

1 answer

A radioactive nucleus can decay by two different process . The half life for first process is $\;t_{1}\;$ and that for second process is $\;t_{2}\;$. Find the effective half life of nucleus

asked Feb 27, 2014 by yamini.v

1 answer

Given a G.P. with $a=729$ and $7^{th}$ term is $64$. Find $S_7.$

asked Feb 27, 2014 by rvidyagovindarajan_1

1 answer

Optical and isomers are compounds which contain the same number and kinds of atoms, and bonds (ie the connectivity between atoms is the same), and different spatial arrangements of the atoms, but which have non-super imposable mirror images. Each non-super imposable mirror image structure is called an enantiomer. Optical isomers get their name because the plane – polarized light that is passed through a sample of a pure enantiomers is rotated. The planeis rotated in the opposite direction but with the same magnitude when plane- polarized light is passed through a pure sample containing the other enantiomer of a pair. A solution of one enantiomer rotates the plane of polrisation in a clockwise direction. This enantiomer is known as the (+) form. A solution of the other enantiomer rotales the plane of polarisation in an anti-clockwise direction. This enantiomer is known as (-) form.

asked Feb 27, 2014 by meena.p

0 answers

The mean lives of radioactive substance are 1620 year and 405 year for $\;\alpha\;$ emission and $\;\beta\;$ emission respectively . Find time during which $\;{\large\frac{3}{4}}^{th}\;$ of a sample will decay if it is decaying both by $\;\alpha\;$ emission and $\;\beta\;$ emission simultaneously .

asked Feb 27, 2014 by yamini.v

1 answer

The disintegration rate of a radioactive sample at a certain instant is 4750 dpm . Five minute later rate becomes 2700 disintegration per minute ; Then the half-life of sample is

asked Feb 27, 2014 by yamini.v

1 answer

Ketanol tautomerism refers to a chemical equilibrium between a keto form (a ketone or an aldehyde) and an enol. The enol and keto fprms are said to be tatutomers of each other. The interconversion of the two forms involved the movements of a proton and the shifting of bonding electrons. A compound containing a carbonyl group $(C=0)$ is normally in rapid equilibrium with an enol tautomer, which contains a pair of doubly bonded carbon atoms adjacent to a hydroxyl $(-OH)$ group, $C=C-OH$ For a carbonyl compound to exhibit tautomerism, the essential condition is that, it must have at least one $ \alpha -H$ atom. Generally , the keto form is more stable than the enol form due to the greater strength of the carbon- oxygen $\pi$ bond as compared - carbon $\pi$ bond. In keto-enol tautomerism of dicarbonyl compounds, the enol form is preferred in contrast to the keto- form , this is due toMaximum enol content is observed in

asked Feb 27, 2014 by meena.p

1 answer

Which of the following organic compound shows Keto–enol tautomerism?

asked Feb 27, 2014 by meena.p

1 answer

Ketanol tautomerism refers to a chemical equilibrium between a keto form (a ketone or an aldehyde) and an enol. The enol and keto fprms are said to be tatutomers of each other. The interconversion of the two forms involved the movements of a proton and the shifting of bonding electrons. A compound containing a carbonyl group $(C=0)$ is normally in rapid equilibrium with an enol tautomer, which contains a pair of doubly bonded carbon atoms adjacent to a hydroxyl $(-OH)$ group, $C=C-OH$ For a carbonyl compound to exhibit tautomerism, the essential condition is that, it must have at least one $ \alpha -H$ atom. Generally , the keto form is more stable than the enol form due to the greater strength of the carbon- oxygen $\pi$ bond as compared - carbon $\pi$ bond. Keto- enol tatutomerism is observed in

asked Feb 26, 2014 by meena.p

1 answer

The sum of first three terms of a G.P. is $16$ and the sum of next three terms is $128$. Find the $1^{st}$ term, common ratio and the sum of $n$ terms of the G.P.

asked Feb 26, 2014 by rvidyagovindarajan_1

1 answer

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