NEET Unit Test - 5 - NEET MCQ

The force between q & Q-q is given by :-
F = kq(Q-q)/r²
As it is given that force between these two is Maximum....so it will be max. when dF/dq is zero
i.e, dF/dq = {k(Q-2q)}/r² = 0
so, Q = 2q
Q/q = 2/1

Where E=0 this point is called neutral point.
it is the point where electric field of both charge is same
we know tha t E=kQ/r²
here k=1/4pi€
for 4q charge
let at ''a'' distance we get E=0 which is from q charge
so distance from 4q of 'a' point is 30-a
electric field by 4q charge on a is
E=k4q/(30-a)²
electric field by q charge on a point
E=kq/a^2
both electric field are equal so put them equal
k4q/(30-a)^2=kq/a²
solve this we get
4a^2=(30-a)²
2a=30-a
3a=30
a=10
so at a distance 10cm from charge q we get E=0
distance from 4q charge 30-10=20cm.

A polarized dielectric is equivalent to two charged surfaces with induced charges (polarization charges). 

• Polar molecules occur when two atoms do not share electrons equally in a covalent bond.
• The oxygen side of the molecule has a slight negative charge, while the side with the hydrogen atoms has a slight positive charge.
• Ethanol is polar because the oxygen atoms attract electrons because of their higher electronegativity than other atoms in the molecule.

• When an external electric field is applied to the conductor, the free electrons in the conductor move in an opposite direction to that of the applied electric field.
• This movement of electrons induces another electric field inside the conductor which opposes the original external electric field.
• This continues until the induced electric field cancels out the external field. 

The displacement of charges inside the dielectric stops when the external force on the charges of the molecules is balanced by the force due to internal fields.

According to Ohm’s law, V = IR. Therefore R= V/I

Power P= V²/R​
If length reduced 10% then new resistance of filament will be R′.
R′=R−10% of R
R′=0.9R
Now new power of heater is P2​
P_2​= V²​​/R′ = V²/0.9R​​=1.1P
% increase power=11%

According to Ohm’s law, V=I R. Therefore R=V/I

Potentiometer is a long wire of uniform cross section made of manganin.

Normality and molarity of a solution are not always equal. Normality depends on chemical  equivalent of the substance while molarity depends on the molecular mass of the substance.

Raoult's law holds over the entire concentration range x = 0 to 1 in a binary solution then, for the second component, the same must also hold.
If deviations from the ideal are not too large, Raoult's law is still valid in a narrow concentration range when approaching x = 1.  for the majority phase (the solvent)  The solute also shows a linear limiting law, but with a different coefficient. This law is known as Henry's Law.

The mole fraction of a gas in solution is related to partial pressure of the gas above the solution by Henry’s law.

Note: K_h (Henry’s law constant) is in pressure unit, hence we use relation, Concentration xK_H = Pressure

For E_cell to be highest [H⁺]_a should be lower and [H⁺]_c should be higher and that why anode compartment should be more basic and cathodic compartment should be acidic. 

The microsporangial wall’s outer three layers—the epidermis, endothecium, and middle layers—help to shield developing anthers and act as a mechanism for dehiscence in adult anthers.

Microsporangium is surrounded by four wall layers. The innermost layer is tapetum. Tapetum nourishes the developing pollens. The three outer walls provide protection and help in dehiscence of anther to release pollen grains.

Pollen grain consists of hard covering of exine but their viability may lost with time. For Hybridisation pollen grains are collected and stored in liquid nitrogen below -196 degree Celsius temperature.

Inbreeding occurs in intraspecific flowers as contain same kinds of genetic materials. Outbreeding takes place between interspecific flowers having different kinds of genetic materials.

• Stigma - It is the head of the pistil.
  • It receives pollen, which begins the process of fertilization.
• Style - It the stalk of the pistil.
  • It is a long, slender stalk that connects the stigma and the ovary. 
  • When pollen reaches the stigma, it begins to grow a tube through the style called a pollen tube, which eventually reaches the ovary.
• Ovary - It is the base of the pistil.
  • It holds the ovules for fertilization.
• Thalamus - It is present near the stalk of the flower.
  • It supplies nutrients to the flower.
  • It is a condensed axis of the flower from which all floral parts arise.

Endosperm cells are triploid as they are formed by triple fission of two polar nuclei and one male gamete. So, haploid cell will contain 8 chromosomes only. Root cells are diploid. Hence root cell will contain 16 chromosomes.

Explanation for Correct option:
Flowers have a role in plant sexual reproduction. The sexual reproduction process results in the formation of seeds. Fruits are the protective covering for seeds. Sexual reproduction encompasses all three. Flowering plants, often known as angiosperms, reproduce in a sexual manner. Plant reproduction is primarily centered on the flower, which contains both male and female gametes. Although some components of bloom are sterile, they all help in the reproduction process.

Final answer: Flower, seed, and fruit take part in sexual reproduction.

As in the case of any other cell, sperms are enveloped by a phospholipid bilayer, which is also called as plasma membrane or cell membrane.