Chemistry - Study Mode

[#101] When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy siate, they emit light, which we can observe in
Correct Answer

(C) Emission spectra

Explanation

Solution: The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state. The photon energy of the emitted photon is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has a specific energy difference. This collection of different transitions, leading to different radiated wavelengths, make up an emission spectrum. Each element's emission spectrum is unique. Therefore, spectroscopy can be used to identify elements in matter of unknown composition. Similarly, the emission spectra of molecules can be used in chemical analysis of substances.

[#102] If the equilibrium constants for the systems H 2 + I 2 -> 2HI and 2HI -> H 2 + I 2 are K 1 and K 2 respectively, the relationship between K 1 and K 2 is :
Correct Answer

(D) K 1 = 1/K 2

Explanation

Solution: Relationship between K 1 and K 2 is K 1 = 1/K 2

[#103] The influence of temperature on reaction rate is predicted by
Correct Answer

(C) Arrhenius equation

Explanation

Solution: The main reason that temperature increases the rate of reaction is that more of the colliding particles will have the necessary activation energy resulting in more successful collisions (when bonds are formed between reactants). The influence of temperature is described by the Arrhenius equation.

[#104] Which among the following is used as a catalyst in the production of high octane fuels?
Correct Answer

(B) H 2 SO 4

Explanation

Solution: Sulphuric acid is used as a catalyst for refining and for producing alkylate, an essential component of high octane fuel. The hydrocarbon molecules are reformed into more complex molecules with a higher octane rating value.

[#105] Catalytic converters are generally made from :
Correct Answer

(C) Transition metals

Explanation

Solution: Transition metals are used directly as catalysts in the anti–pollution catalytic converters in car exhausts. For example, expensive transition metals such as Platinum and rhodium are used in the catalytic converters in car exhausts to reduce the emission of carbon monoxide and nitrogen monoxide, which are converted to the non–polluting gases nitrogen and carbon dioxide. 2NO(g) + 2CO(g) ⇒ N 2 (g) + 2CO 2 (g)