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Match List-I with List-II:
| List-I | List-II |
|---|---|
| A. Coke | I. Carbon atoms are sp³ hybridised. |
| B. Diamond | II. Used as a dry lubricant. |
| C. Fullerene | III. Used as a reducing agent. |
| D. Graphite | IV. Cage-like molecules. |
Choose the correct answer from the options below:
Coke: reducing agent. Diamond: sp³. Fullerene: cage. Graphite: dry lubricant.
Given below are two statements: one is labelled Assertion A and the other Reason R.
Assertion A: A reaction can have zero activation energy.
Reason R: The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to threshold value is called activation energy.
In the light of the above statements, choose the correct answer:
Zero $E_a$ is possible if reactants already possess threshold energy; R correctly defines $E_a$ and explains A.
Homoleptic complex from the following complexes is:
Homoleptic = all ligands identical. Only (A) contains a single ligand type (oxalate).
A compound is formed by two elements A and B. The element B forms cubic close packed structure and atoms of A occupy 1/3 of tetrahedral voids. If the formula of the compound is $A_x B_y$, then the value of $x + y$ is:
In ccp, atoms = 4; tetrahedral voids = 8. A fills $8/3$. Ratio A:B $= 8/3 : 4 = 2:3$, so formula $A_2B_3$, $x+y=5$.
The right option for the mass of CO₂ produced by heating 20 g of 20% pure limestone is (Atomic mass of Ca = 40):
$$\text{CaCO}_3 \xrightarrow{1200\,\text{K}} \text{CaO} + \text{CO}_2$$
Pure CaCO₃ = 4 g $\Rightarrow$ moles = 0.04. CO₂ mass = $0.04 \times 44 = 1.76\ \text{g}$.
Taking stability as the factor, which one of the following represents correct relationship?
Inert pair effect: for Tl, +1 state is more stable than +3 → TlI more stable than TlI₃.
Identify product (A) in the following reaction:
$$\xrightarrow[\text{conc. HCl}]{\text{Zn-Hg}}\ (A) + 2\,\text{H}_2\text{O}$$
Clemmensen (Zn-Hg/HCl) reduces C=O of ketones completely to CH₂. Each –COCH₃ becomes –CH₂CH₃ (ethyl).
Select the correct statements:
A. Atoms of all elements are composed of two fundamental particles. B. The mass of the electron is $9.10939 \times 10^{-31}$ kg. C. All the isotopes of a given element show same chemical properties. D. Protons and electrons are collectively known as nucleons. E. Dalton's atomic theory, regarded the atom as an ultimate particle of matter.
A wrong (3 particles: p, n, e). D wrong (nucleons = p + n, not p + e). B, C, E correct.
For a certain reaction, the rate $= k[A]^2[B]$. When the initial concentration of A is tripled keeping concentration of B constant, the initial rate would:
Rate $\propto [A]^2$; tripling A $\Rightarrow$ rate $\times 3^2 = 9$.
Given below are two statements:
Statement I: A unit formed by the attachment of a base to 1'-position of sugar is known as nucleoside.
Statement II: When nucleoside is linked to phosphorus acid at 5'-position of sugar moiety, we get nucleotide.
Choose the correct answer:
Standard definitions of nucleoside (base + sugar) and nucleotide (nucleoside + phosphate at 5′).
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