The body weight of offspring of bird species is range between 12 gm to 18 gm. In a laboratory experiment, species was subjected to selection pressure having influence on the offspring body weight. After many generations of experimental selection pressure, the body weight range between 16 gm to 24 gm. Which of the following natural selection operate on this species?

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#Question id: 20250

#XL - P Chemistry

What is the work done against the atmosphere when 25 grams of water vaporizes at 373 K against a constant external pressure of 1 atm ? Assume that steam obeys perfect gas laws. Given that the molar enthalpy of vaporization is 9.72 kcal/mole, what is the change of internal energy in the above process ?

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#Question id: 20251

#XL - P Chemistry

In the reaction CS2 (l) + 3O2 (g) → CO2 (g) + 2SO2 (g) ΔH = –265 kcal

The enthalpies of formation of CO2 and SO2 are both negative and are in the ratio 4 : 3. The enthalpy of formation of CS2 is + 26 kcal/mol. Calculate the enthalpy of formation of SO2.

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#Question id: 20252

#XL - P Chemistry

The bond dissociation energy of gaseous H₂, Cl₂ and HCl are 104, 58 and 103 kcal mol^{– 1} respectively. The enthalpy of formation for HCl gas will be

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#Question id: 20253

#XL - P Chemistry

AB, A2 and B2 are diatomic molecules. If the bond enthalpies of A2, AB & B2 are in the ratio 1 : 1 : 0.5 and enthalpy of formation of AB from A2 and B2 is – 100 kJ/mol^–1. What is the bond enthalpy of A2.

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#Question id: 20254

#XL - P Chemistry

Given the following data

Determine at what temperature the following reaction is spontaneous ?

FeO(s) + C (Graphite)→ Fe(s) + CO(g)

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#Question id: 20255

#XL - P Chemistry

One mole of a gas occupying 3 dm³ expands against constant external pressure of 1 atm to a volume of 13 dm³. The work done is –