Monthly Mock Test (October 31) - NEET MCQ

Charge resides on the outer surface of a conducting hollow sphere of radius R. We consider a spherical surface of radius r < R.
By Gauss's theorem,

i.e. electric field inside a hollow sphere is zero.

Some fleshy fruits such as mango, plum etc. usually have a single hard stone that encloses a seed, called drupe.

Ovule is also called integumented megasporangium. It develops into seed after fertilisation in spermatophytes. It occurs singly or in a cluster inside ovary with parenchymatous cushions called placenta.

Wind pollination is common in grasses. Grasses produce large amount of pollen which by the help of wind reach to opposite sex for reproduction.

ΔT_f = 0 – (0.00732°) = 0.00732
ΔT_f = i × K_f × m

Given : Length of the dipole (2l) =10cm
= 0.1m or l = 0.05 m
Charge on the dipole (q) = 500 μC = 500 × 10^–6 C and distance of the point on the axis from the mid-point of the dipole (r) = 20 + 5 = 25 cm = 0.25 m. We know that the electric field intensity due to dipole on the given 

Sporogenous tissue is always diploid, endothecium is second layer of anther wall and perform the function of protection and help in dehiscence of anther to release the pollen. Hard outer layer of pollen is called exine but tapetum always nourishes the developing pollen.
Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus (polypoid).

Given K_f = – 1.86º cm^–1, mass of solute = 5.00 g, mass of solvent = 45.0 g

∴ i = 2.63 (Molecular mass of Na₂SO₄ = 142)

Perisperm is remnants of nucellus which is diploid (2n) but endosperm is triploid (3n). Perisperm occurs in the seeds of Black pepper, coffee, castor, cardamum, Nymphaea. Endosperm is the food  laden tissue which is meant for nourishing the embryo in seed plants. In angiosperms the endosperm is formed as a result of vegetative fertilization, triple fusion or fusion of a male gamete with diploid secondary nucleus of the central cell.

There are different types of vectors involved in pollination. For example, Maize, mulberry → pollination by wind. Vallisneria → pollination through water (hydrophily). Cucumber → Bees are brought for the commercial plantings of cucumber.

Net force on each of the charge due to the other charges is zero. However, disturbance in any direction other than along the line on which the charges lie, will not make the charges return.

Intensity of electric field due to a Dipole

In over 60 per cent of angiosperms, pollen grains are shed at cell 2-celled stage. In the remaining species the generative cell divides mitotically to give rise to the two male gametes before pollen grains are shed (3-celled stage.)

Cleistogamous flowers do not expose their reproductive parts. Anthers and stigma lie close to each other. Pure autogamy occurs since there is no chance of crosspollination. Cleistogamy is the most efficient floral adaptation for promoting self-pollination. E.g., Viola mirabilis and Oxalis autosella.

(b) Pollination by wind is called anemophily. Wind pollinated flowers are small in size, producing large number of dry pollen grains. Pollens are small, dry and light in weight. Grasses are anemophilous plants.

Osmosis is the phenomenon of flow of pure solvent from the solvent to the solution or from a less concentrated solution to a more concentrated solution through a semipermeable membrane. Common semipermeable membranes are permeable to certain solute particles also. In fact, there is no perfect semipermeable membrane. Therefore we can say that flow of water through a semipermeable membrane takes place on both sides with unequal rates.

Nucellar polyembryony is reported in a Citrus species.

An ideal solution is that solution in which each component obeys Raoult’s law under all conditions of temperatures and concentrations. For an ideal solution.

The germ pores are apertures in the exine layer of the pollen grain where the sporopollenin is absent. The germ pore helps in the formation of the germ tube or pollen tube and which makes its exit on germination. 

Endosperm is the nutritive tissue which provides nourishment to the embryo in seed plant. Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor, sunflower).

Commelina bears aerial, chasmogamous (stigma and anthers exposed to pollinating agents), insect pollinated flowers and underground cleistogamous flowers. Cleistogamous flowers are bisexual flowers which never open. In such flowers, the anther and stigma lie very close to each other. When anther dehisce in the flower buds, pollen grains come in contact with the stigma of the same flower i.e, autogamy occurs. So, these flowers produce an assured seed set, even in the absence of pollinators.

Pollen grains are generally spherical and a prominent two-layered wall. The hard outer layer called the exine is made up of sporopollenin which is one of the most resistant organic material known. It can withstand high temperatures and strong acids and alkali.

The correct answer is option C
Molar mass of CH₂​Cl₂​ =12×1+1×2+35.5×2=85 g mol^–1
Molar mass of CHCl₃ ​  =12×1+1×1+35.5×3=119.5 g mol⁻¹
Moles of CH_2​Cl₂​= 40 g /85 g mol−1 = 0.47 mol
Moles of CHCl₃​ = 25.5 g /119.5 g mol−1 = 0.213 mol
Total number of moles = 0.47+0.213=0.683 mol
Mole fraction of component 2
 =0.47mol/0.683mol= 0.688
Mole fraction of component 1
=1.00–0.688=0.312 
We know that:
P_T​=p₁⁰​+(p₂⁰​−p₁⁰​)x2​
=200+(415–200)×0.688
=200+147.9
=347.9 mm Hg

Dipole is formed when two equal and unlike charges are placed at a short distance.

Given α = 30% i.e., 0.3

i = 1.3
ΔT_f = 1.3 × 1.86 × 0.1 = 0.2418
T_f = 0 – 0.2418 = – 0.2418 °C

Concentration of

[Na⁺] = 2 × 0.955 = 1.91 M

= 0.955 M

Charges (q) = 2 × 10^-6 C,

Distance (d) = 3 cm = 3 × 10^-2 m

and electric field (E) = 2 × 10⁵ N/C. Torque (t) = q.d.

E = (2 × 10^-6) × (3 × 10^-2) × (2 × 10⁵)

= 12 × 10^-3N-m.

Cleistogamy favours no dependence on pollinator because flowers never open. In such flowers, the anthers and stigma lie close to each other. When anthers dehisce in flower buds pollen grains come in contact with the stigma to effect pollination.