NEET Unit Test - 8 - NEET MCQ

The maximum kinetic energy for the photoelectrons is 
E_max​=hν−ϕ
where, ν is the frequency of incident light and ϕ is photoelectric work function of metal.
eV_0​=hν−ϕ ...................(1)
where, V₀​ is the stopping potential and e is the electronic charge.
When, the frequency of light in a photoelectric experiment is doubled, 
eV₀′​=2hν−ϕ 
eV₀′​=2[hν−(ϕ/2​)].........................(2)
From the above two equations we can say that the K.E. in (2) is more than double of K.E in (1). Hence, when the frequency of light in a photoelectric experiment is doubled, the stopping potential becomes more than double.
So, the answer is option (C).

We know that,
eV=(hc/λ)-w
V=(hc/eλ)-(w/e)
Arithmetic progression =>V₂=(V₁+V₂)/2
Now,
(hc/eλ₂)-w/e=1/2[(hc/eλ₁)-(w/e) +(hc/eλ₃) -(w/e)]
=>1/ λ₂=1/2[(1/ λ₁)+(1/λ₃)]
=>2/ λ₂=1/ λ₁ + 1/λ₃
Hence the correct answer is harmonic Progression.

Nuclear force remains the same for all nuclei. Hence the reason is false.

A is false but R is true
Explanation: The isotopes are indeed atoms of the same element with different atomic masses due to different numbers of neutrons. However, they do not require different positions in the periodic table. Isotopes of the same element share the same chemical properties and thus occupy the same position in the periodic table. The atomic number, which determines an element's place in the periodic table, remains the same for all isotopes of a given element.

In nuclear reactors, fission of uranium is carried out by bombarding  a slow moving neutron on uranium which results in emission of 3 more neutrons along with the byproducts  So, cadmium rods are used to absorb extra neutrons in order to achieve controlled chain reaction.

The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit (amu, also known as daltons, D). The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope.

A hydrogen atom has magnetic properties because the motion of the electron acts as a current loop. The energy levels of a hydrogen atom associated with orbital angular momentum are split by an external magnetic field because the orbital angular magnetic moment interacts with the field.

1/ λ =Z². (both have same transition so same value of n)
λ /122=1/16
λ =122/16
=7.62nm

There are two types of semiconductors: p-type and n-type. Therefore both holes and electrons conduct current respectively.

Electrons in metal behave as gas.

Alcohols have higher boiling points than aldehydes.

In this reaction, a CO group is converted to CH_2​ group.

This can be achieved by Wolff-Kishner reduction which uses reagent NH₂​NH₂​, OH⁻ (hydrazine in alkaline medium).

Clemmensen reduction (Zn(Hg)/HCl) cannot be used as in presence of HCl, the alcohol may undergo dehydration.

Fe + HCl is preferred due to the following reasons:
- Scrap iron i.e Fe is cheap and commercially easily available
- FeCl₂ formed will get hydrolysed and release HCl, so, HCl which is required in the reaction will be produced by itself
- Hence only small amount of HCl is required to initiate the reaction.

The correct answer is Option D.

The correct answer is option D
The chemical reaction used for transforming primary alkyl halides into primary amines is called Gabriel phthalimide synthesis. It uses potassium phthalimide. Therefore, Gabriel phthalimide synthesis is used in the preparation of 1o
amide.

Sucrose, commonly known as cane sugar, is a type of disaccharide. When it undergoes hydrolysis, it breaks down into simpler sugars.

The hydrolysis of one molecule of sucrose yields:

As a result, the correct breakdown can be summarised as:

This process is important for digestion and energy production in the body.

In α-helix, hydrogen bonds are present between –NH group of one amino acid residue to the >C= O group of another aminoacid residue.

If all members fo a host species die the parasite that obtain their food from the particular host also die off due to lack of food. This represent co-existence of species.

When we will move away from the equator towards poles there is a gradual decrease in the species diversity. This is because climatic condition becomes gradually adverse as we move from equator to poles.

Wetlands are areas where water is the primary factor controlling the environment and the associated plant and animal life. They occur where the water table is at or near the surface of the land, or where the land is covered by water.

India has about 50,000 type of rice and 1000 types of varieties of mango. This thigh level of diversity indicates very high genetic diversity and one of the largest in the world.

The materials or substances occurring in nature that exist without the actions of humankind are known as natural resources. The conservation of natural resources is important for the preservation of natural, biological diversity.

In the ecosystem, the flow of energy takes place in only one direction i.e. from producers to final consumers.
The energy present in one trophic level never returns back to the producer.

Energy flow in our ecosystem:

Aquatic Food Chain:

Primary productivity is the amount of biomass produced per unit area by green plants in an ecosystem. Producers fix the solar energy by the process of photosynthesis.

The chromosomal pattern in the amniotic fluid is detected using the technique called amniocentesis. This chromosomal pattern is called karyogenesis and can be used to detect the nature of chromosomes. Hence it can be exploited to determine sex of the fetus.

Fetal sex determination is based on the patterns of chromosomes in the amniotic fluid present around the embryo. Hence this test is called amniocentesis.

Plasmodium completes their life cycle in two hosts, female anopheles and human beings. The motile zygote of plasmodium occurs in gut of female anopheles, which get transferred to human being during mosquito bite.