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.

The electron orbiting around the nucleus radiates energy. As a result, the radius of the orbit continuously decreases and the electrons fall into the nucleus. So, the stability of atoms is not explained. Hence the reason is true.

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.

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

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.

Reversibility of aldol into carbonyls establishes that carbanion nucleophile is formed in first fast reversible step.

It would be true only if both carbonyls are capable of forming enolates, i.e. possesses α-H

Product is an acetal, more stable than hemiacetal reactant. Acetal is formed via carbocation, both diastereomers are formed.

LiAlH₄ reduces all oxiginated functional groups to alcohol and all nitrogenated functional groups to amine thus cyanide is a nitrogenated functional group and to convert cyanide to amine LiAlH4 can be used.

If blood glucose levels become too low, glucagon (pancreatic hormone) is released, which causes the liver to convert the stored glycogen back into glucose, and release it into the bloodstream.

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:

• 1 molecule of glucose
• 1 molecule of fructose

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

• Glucose: a simple sugar that provides energy.
• Fructose: another simple sugar, found in many fruits.

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

 Flavor, texture and shortening are all major culinary uses of oil in the food industry.

Thymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. In RNA, thymine is replaced by the nucleobase uracil.

Species area relationship is the relationship between the area and the particular habitat. It is dependent on immigration, extinction and clustering etc. It was first studied by Alexander Von Humbolt.

International Union for Conservation of Nature (IUCN) was founded on 5 October 1948 in France by Julian Huxley. It is working in the field of conservation of nature and sustainable use of natural resources.

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:

The components of the ecosystem are seen to function as a unit when the aspect is decomposition.

• It is a part of the nutrient cycle in which organic substances are broken down into simpler organic matter.

Nepenthes (pitcher plant) and Drocera are insectivores plants to compensate for their protein requirement. They have green leaves that perform the photosynthesis process. So, they act as both producers as well as consumers.

Ecosystem is the functional and dynamic unit of nature where living and non-living components interact with each other for flow of energy and biomass from producer to consumers.

Saheli is a contraceptive for females. It prevents unwanted pregnancy. It is an oral pill. It is Ormeloxifene, marketed under the brand name Saheli. It is a selective estrogen receptor modulator or SERM.

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.

Reproduction-related problems are ones that affect reproductive health. These include difficulties in pregnancy and delivery, STDs, abortions, menstrual problems, infertility, contraception, and many more.

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.

• Typhoid fever in the human being is caused by Salmonella typhi.
• The pathogen enters the small intestine through food and contaminated water and migrates to other organs through blood

This illustration depicts a photomicrograph of Salmonella typhi bacteria:

The release of toxic haemozoin by the ruptured RBCs during malarial infection accounts for the recurrence of high fever and chill every 3-4 days.

Antibodies in our body are present in the blood in form of glycoproteins. They produce antigens in response to foreign particles to provide immunity against the pathogen.