- The coldest region of the atmosphere
(a) Troposphere
(b) Thermosphere
(c) Stratosphere
(d) Mesosphere
Answer: d
Video Explanation
22.Regular use of which of the following fertilizers increases the acidity of soil?
(a) Potassium nitrate
(b) Superphosphate of lime
(c) Ammonium sulphate
(d) Urea
Answer: c
Video Explanation
- Find the incorrect statement
(a) BOD value of clean water is less than 5 ppm
(b) Drinking water pH should be between 5.5-9.5
(c) carbon, sulphur and nitrogen oxides are the most widespread air pollutants
(d) dissolved oxygen concentration below 5 ppm is ideal for the growth of fish,
Answer: d
Explanation
Biochemical oxygen demand (BOD) represents the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature.
Video Explanation - Which of the species is not paramagnetic?
(a) As+
(b) Cl–
(c) Ne2+
(d) Be+
Answer: b
Video Explanation - C-O bond length is minimum in
(a) CO2
(b) CO32-
(c) CO
(d) all has same
Answer: d
Explanation
Method (1) Bond-multiplicity increases bond-length. Thus, (i) C≡ → has least bond-length. (ii) O=C+O→ next to C=O. Hence, increasing order of bond-length is CO<CO2<CO32− Method (2) (i) More be the value of bond-order smaller be the bond-length and more be the bond-energy.
(ii) Bond order (BO)= Total number of bonds associated between two atoms in all structure/ Total number of canonical forms (a) CO→C≡O→BO=13=3 (b) CO2→O=C=C→BO=24=2 Hence, order of bond-length CO<CO2<CO32−
Video Explanation - Which of the following reactions may be associated with aldehyde and ketone?
(a) Nucleophile addition
(b) Polymerization
(c) Oxidation
(d) All of the above
Answer: d
Explanation
The nucleophilic addition reaction between hydrogen cyanide (HCN) and carbonyl compounds (generally aldehydes and ketones) results in the formation of cyanohydrins. Base catalysts are often used to increase the rate of the reaction.
aldehyde condensation polymer, any of a number of industrially produced polymeric substances (substances composed of extremely large molecules) that are built up in condensation reactions involving an aldehyde.
Aldehydes have a proton attached to the carbonyl carbon which can be abstracted, allowing them to be easily oxidized to form carboxylic acids. The lack of this hydrogen, makes ketones generally inert to these oxidation conditions. Nevertheless, ketones can be oxidized but only under extreme conditions.
Video Explanation - Sp3d2 hybridization is present in [Co(NH3)63+], find its geometry
(a) octahedral geometry
(b) square planar geometry
(c) tetragonal geometry
(d) tetrahedral geometry
Answer: a
Video Explanation - For the same value of n, the penetration power of orbital follows the order
(a) s = p = d = f
(b) p > s > d > f
(c) f < d < p < s
(d) s < p < d < f
Answer: c
Video Explanation - Which of the following statements is incorrect?
(a) I.E.1 of O is lower than that of N but I.E.2 O is higher than that of N
(b) isoelectronic ions belong to the same period
(c) The enthalpy of N to gain an electron is almost zero but of P is 74.3 kJ mol-1
(d) none of these
Answer: b
Video Explanation - Which one will have the highest 2nd ionization energy?
(a) 1s2 2s2 2p4
(b) 1s2 2s2 2p6 3s1
(c) 1s2 2s2 2p6
(d) 1s2 2s2 2p6 3s2
Answer: b
Video Explanation - In the rate equation, when the concentration of reactants is unity then the rate is equal to
a) specific rate constant
b) average rate constant
c) instantaneous rate constant
d) None of the above
Answer: a
Video Explanation - Which of the following observations is incorrect about the order of a reaction?
(a) Order of a reaction is always a whole number
(b) The stoichiometric coefficient of the reactants doesn’t affect the order
(c) Order of reaction is the sum of power to express the rate of reaction to the concentration terms of the reactants.
(d) Order can only be assessed experimentally
Answer: a
Video Explanation - In the reaction 2A + B → A2B, if the concentration of A is doubled and that of B is halved, then the rate of the reaction will
(a) increase 2 times
(b) increase 4 times
(c) decrease 2 times
(d) remain the same
Answer: a
Video Explanation - The number of milligrams of KOH required to neutralize the free and combined fatty acid in one gram of a given fat is called __
(a) Polenske number
(b) Acid number
(c) Iodine number
(d) none of these
Answer: d
Explanation
The Polenske value (also known as the Polenske number) is a value determined when examining fat. It is an indicator of how much volatile fatty acid can be extracted from fat through saponification.
Acid value is the mass of potassium hydroxide in milligrams that is required to neutralize one gram of chemical substance.
Iodine no a measure of the unsaturation of a substance (as an oil or fat) expressed as the number of grams of iodine or equivalent halogen absorbed by 100 grams of the substance
The saponification value is defined as “the number of milligrams of KOH needed to neutralize the fatty acids obtained by complete hydrolysis of 1gram of an oil sample.”
Video Explanation - Gluconeogenesis involves the______.
(a) synthesis of glycogen from glucose
(b) breakdown of glycogen to form glucose
(c) breakdown of glucose to produce pyruvate
(d) None of the these
Answer: d
Explanation
Gluconeogenesis is the pathway by which glucose is synthesized from non-carbohydrate metabolites. The principal gluconeogenic precursors are pyruvate and lactate, certain gluconeogenic amino acids, and glycerol, which is derived mainly from fat metabolism.
Video Explanation - Which of the following disaccharides gives two same monosaccharide units on hydrolysis?
(a) Maltose
(b) Sucrose
(c) Lactose
(d) none of these
Answer: a
Explanation
A dissacharide consists of two sugars joined by an O-glycosidic bond. In a dissacharide, two monosaccharides are joined together by acetal or glycoside formation. The hemiacetal OH of one monosaccharide and OH of second monosaccharide dehydrate to establish the bond called glycosidic bond.
Maltose is a disaccharide which is made up of the same monosaccharide units. As you can see in the next figure
Video Explanation - Which of the following tests does glucose give?
(a) Addition product with NaHSO3
(b) 2,4-DNP test
(c) Schiff’s test
(d) none of these
Answer: d
Video Explanation - Which of the following substance produce acetaldehyde on dry distillation?
(a) (CH3COO)2Ca
(b) (HCOO)2Ca
(c) Both A and B
(d) None
Answer: C
Video Explanation - Which of the following substances does not give iodoform test?
(a) Acetaldehyde
(b) Ethyl alcohol
(c) Methyl alcohol
(d) Acetone
Answer: c
Explanation
Iodoform test is used to check the presence of carbonyl compounds with the structure R-CO-CH3 or alcohols with the structure R-CH(OH)-CH3 in a given unknown substance. The reaction of iodine, a base and a methyl ketone gives a yellow precipitate along with an “antiseptic” smell.
Video Explanation - Which of the following compounds will react with Tollen reagent?
(a) CH3-CHO
(b) CH3-CH-CH3
(c) CH3-COOH
(d) CH3-CO-CH2-CH3
Answer: a
Explanation
Tollens test is generally given by compounds having aldehydic group (aldehydes,alpha-hydroxy ketones and formic acid-its -COOH behaves like a aldehydic group). It gives a white ppt of Silver (where the silver salt is reduced to silver metal and the aldehyde is oxidised to silver salt of carboxylic acid.
Video Explanation
