Physics, Chemistry, Mathematics Forums

i have a very small doubt that, why electric field is not present near a current carrying wire? 

I have few ques. of energetics.... plz can u suggest me some answer for them... I will be having the correct answer in a few days...

Q1. Which of the following statements is/are true for a gas?

A) For an ideal gas, if the expansion is against a vacuum, no cooling or heating is observed.
B) For a real gas expanding in vacuum, its temperature can be increased or decreased depending upon whether its temperature is above or below the inversion temp. resp.
C) For a real gas, internal energy is a function of its temperature as well as volume.
D) All of the above.

Q2. Choose the correct statement(s)
A) Exothermic reactions proceeding with a decrease in entropy tends to become non-spontaneous at higher temp.
B) Endothermic rxn. proceeding with an increase in entropy tends to become spontaneous at higher temp.
C) Highly non-spontaneous rxns. can be coupled with highly spontaneous rxns to make the former spontaneous.
D) Entropy of a crystalline substance(pure or impure) is always 0 at 0 K.

In this ques. i just have doubt in option (D). The rest should be correct according to me.

Q3. Which of the following(s) is/are INCORRECT statements?
A) A gas expanding against a constant pressure is an example of irreversible reaction.
B) For isolated systems, the direction of spontaneity can always be predicted by the direction of increase in entropy.
C) For a substance of standard state, its Gibbs free energy and enthalpy can be taken as zero.
D) W_reversible > W_irreversible (always) where W = work done during expansion of a gas.

Q4. Which one of the following is/are correct?
A) The net increase in entropy of the system is zero in any reversible cyclic process.
B) The isothermally available energy present in a system is called its free energy.
C) The change of free energy with pressure for one mole of a perfect gas at constant temp. is delta G = RT ln(P₂/P₁).
D) For a spontaneous process delta G at const. T and P is zero.

For all these ques. plz give me justifications for your answers.

The asymptotes of a hyperbola given by x = a tan(q + a),  and y =  b tan(q + b)  where q is variable parameter is______( c is any constant)

a) cxy - bx + ay + abc = 0

b) bcx + aby + acxy + abc = 0

c) xy + y² + a + b + c = 0

d) (a + b)x + (c +a)y + (b + c)xy = 0

Please give me the solution to the above problem. 

Someone please clear my previous doubt on Hyperbola.

What will be the product formed from the following reaction:
 
(CH₃)₃C-CH=CH₂    D₂O/H⁺    ?

Also if you know the mechanism, please tell me...

is parabola a function?  ( it gives 2 values of y for 1 value of x)

I had doubt in 2 small questions:-

1. CuSO₄. 5 H₂O contains which type of bonds -

a. Covalent only  b. Covalent and coordinate  c. Covalent, Coordinate,ionic and H-bonds  d. Ionic and covalent only.

The ans. is given as c. Please explain me the ans.

2. This is an objective asked in JEE '98. Answer to this ques. is given different in different books.

What is not correct about white phosphorous P₄ ?

a. It has six P-P single bonds.

b. It has four P-P single bonds only.

c. It has four lone pairs of electrons.

d. It has PPP angle of 60⁰.

I think the answers should be a,c. Please tell me the right ans.

• The concentration of hydrogen ion in a 0.2 M solution of formic acid is 6.4 * 10^-3 moles per litre. To this solution sodium formate is added so as to adjust the concentration of sodium formate one mole per litre. What will be the pH of this solution? The dissociation constant of formic acid is 2.4 * 10^-4 and the degree of dissociation of sodium formate is 0.75

• 2.05g of sodium acetate was added to 100 ml of .1 M HCl solution. Find the H⁺ concentration of the resulting solution. If 6 ml of 1M HCl is further added to it, what will be the new H+ concentration? The dissociation constant of acetic acid is 1.8 * 10^-3.

Plz give solutions with steps. The 1st question was asked at IITJEE1985. the second is from thhe unsolved questions list in R.C. Mukerjee

According to Huygen's principle, the wavelets formed by a progressive wave propagating in an elastic media are always outward from the source.I have not seen any wavelet converging towards the source as it should becasue every point on the wavefronts give birth to new wavelets that spread out in all directions.Could anyone please clarify the reason to me?

I had doubt in some short ans. questions....Please solve them-
1.Can we find the mass of a photon by the definitions p = m v ?
2.What is the speed of a photon w.r.t another photon if
(a) the two photons are going in the same direction
(b) they are going in opposite directions ?
3.Can a photon be deflected by an electric field? By a magnetic field?
4.Should the energy of a photon be called its kinetic energy or internal energy?