NEET Unit Test - 3 - NEET MCQ

Given in question,

Mobilities of electrons μ_e ​= 0.36×m²V⁻¹s⁻¹

Mobilities of holes μ_h ​= 0.17×m²V⁻¹s⁻¹

densities of electron= densities of holes=2.5×10¹⁹m⁻³

As we know, conductivity,
σ=1/p​=e(μ_e​n_e​+μ_n​n_n​)
=1.6×10⁻¹⁹[0.36×2.5×10¹⁹+0.17×2.5×10¹⁹)]
=2.12Sm⁻¹

So the electrical conductivity of germanium is 2.12Sm⁻¹

Explanation:

Hydrogen is a diatomic gas. (C_P = 3.5R)

energy transferred by heat to the gas

Q=nCPΔT=1×3.5×8.31×120=3490J=3.49KJ

Explanation:

for monoatomic gas 

from conservation of energy

PV=nRT

Hence the value of PV/T where the curves meet on the y-axis is 0.26 jK^-1

Explanation:

At const volume, 

Q = 500 J

Q=nCPΔT

500=1×2.5×8.31ΔT

ΔT=24.06

W=nRΔT=1×8.31×24.06=200J

Calculation:

For Case 1 :

For Case 2 :

From (i) and (ii)

288 f_app = 240 × 240

f_app = 200 Hz

J = neV_d
Resistivity, ρ = E/j = E/neV_d = 1/ne(v_d/E) = 1/neμ_e
Resistivity, 1/(10¹⁹ x 1.6 x 10^-19 x 1.6) = 0.39 Ω m = 0.4 Ω m

Explanation:

Helium is a monoatomic gas.(C_V = 1.5R)

change in internal  energy 

ΔU=nCVΔT=3×1.5×8.31×2=75J

Cl₂(g) is formed at anode and NaOH and H₂ are formed at cathode. Since, cathode and anode are separated. Hence. there is no reaction between the products formed at the cathode and anode. 

Note: but these reaction do not occur

Note: NaCl is neutral pH = 7 initially. After electrolysis , NaOH is formed

Hence, solution become, basic pH >7

According to the given information, the solution turns pink when cooled in freezing mixture. So, the equilibrium has shifted in backward direction. So we can say that the reaction is endothermic and ∆H for the reaction is greater than zero. This is because, endothermic reactions have ∆H > 0 and they proceed in reverse direction. 

The correct balanced equation is
2MnO₄^– + 5C₂O₄ ^2– + 16H⁺ → 2Mn²⁺ + 10CO₂ + 8H₂O

The correct answer is Option D.
The concentration of OH- will always equal the concentration of H3O+.
PV = nRT, where R is a constant, and n is the quantity of gas measured in mols. The pH of a substance is related to the concentration of H+,
so if we raise or lower the Temperature or Pressure of pure water, we will alter the Volume (or concentration) of H3O+ and OH- ions. As we alter the concentrations we alter the pH and pOH. The only answer that is true no matter what the volume or concentration may be is D
 

Individual frequencies can be represented as p and q. But for a diploid organism, p and q explain the frequency of allele A and allele a. p² represents AA whereas q² represent aa.

The Hardy-Weinberg principle states that allelic and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. There are five factors which are known to affect the equilibrium. These are gene flow, genetic drift, mutation, genetic recombination and natural selection. In population genetics, gene flow (also known as gene migration) is the transfer of alleles or genes from one population to another. Migration into or out of a population may be responsible for a marked change in allele frequencies (the proportion of members carrying a particular variant of a gene). Genetic drift (also known as allelic drift) is the change in the frequency of a gene variant (allele) in a population due to chance events. Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent. Mutation causes variations in the species, which influences the gene pool. Natural selection favours certain variations over others, resulting in an increase in allelic frequency of the favourable variations in the gene pool. Reproduction is a natural process in all organisms, which as such, does not affect Hardy-Weinberg equilibrium; it would be the genetic recombinations that arise from sexual reproduction, that affect it.

Given figures represent the forelimbs of different vertebrates, which possess the same basic structural plan, i.e., in each case, the forelimb consists of humerus, radio-ulna, carpals, metacarpals and digits. Thus, the skeletal parts of these forelimbs are similar in structure and arrangement, but have different shapes and functions. It depicts the example of homologous structures.

A. Beta diversity - Between community diversity
B. Rich biodiversity - Tropical areas
C. Gamma diversity - Diversity of whole geographical region
D. Extinct species - Dodo
E. Critically endangered species - Great Indian bustard

Earth summit at Rio de Jenerio (1992), Brazil promoted Convention on Biological Diversity (CBD) which was signed by 152 nations. Its recommendations came into effect on 29th Dec. 1993. India became a party to this Convention on Biological Diversity in May, 1994.

Triangular age pyramid has high proportion of reproductive individuals, moderate number of reproductive individuals and fewer post-reproductive individuals. It represents young or rapidly growing population.

In urn-shaped age pyramid, the number of reproductive individuals is higher than the number of pre-reproductive individuals. It represents declining or diminishing population with negative growth

In bell-shaped age pyramid, the number of pre-reproductive and reproductive individuals is almost equal. Post reproductive individuals are comparatively fewer. It represents stable or stationary population where growth rate is nearly zero.

Topic in NCERT: Age Pyramids and Population Growth Status

Line in NCERT: "The shape of the pyramids reflects the growth status of the population - (a) whether it is growing, (b) stable or (c) declining."

Number of deaths is more than the number of births, showing a declining population.

In the given food web, organisms I (phytoplanktons) act as producers, organisms II, V and VII act as primary consumers as they feed on producers, organisms III and VI act as secondary consumers as they upon primary consumers, and organism IV acts as a tertiary consumer.

Topic in NCERT: Trophic Levels in an Ecosystem

Line in NCERT: "Those animals that depend on the primary carnivores for food are labelled secondary carnivores."

- Assertion Evaluation: The assertion is true because nutrient cycling indeed comprises both gaseous (e.g., carbon cycle) and sedimentary (e.g., phosphorus cycle) types, and both are essential for maintaining ecosystem stability.

- Reason Evaluation: The reason is also true as it accurately describes the reservoirs for both cycles; however, it does not explain why both cycles are crucial for ecosystem health or how they interact.

- Conclusion: Since both the assertion and reason are true but the reason does not serve as the correct explanation for the assertion, the correct answer is Option B.

In the given scenario, the laboratory population of fruit flies consists of 40 fruit flies, and during a specified time interval, 4 individuals died. To calculate the death rate, we divide the number of deaths by the total population.

Number of deaths = 4
Total population = 40

Death rate = Number of deaths / Total population
= 4 / 40
= 0.1 individuals per fruitfly per week

Option a) "0.1 individuals per fruitfly per week" is the correct answer because it accurately represents the death rate calculated based on the given information.

Topic in NCERT: Population Dynamics

Line in NCERT: "If 4 individuals in a laboratory population of 40 fruitflies died during a specified time interval, say a week, the death rate in the population during that period is 4/40 = 0.1 individuals per fruitfly per week."

• Hugo de Vries proved mutation theory by doing experiments on Oenothera lamarckian, also known as evening primrose.
• It was from this plant; he came up with the observations.
• It is a complex heterozygous plant with a chromosomal aberration.

Line in NCERT: "In the first decade of twentieth century, Hugo deVries based on his work on evening primrose brought forth the idea of mutations - large difference arising suddenly in that differ from other breeds."

Clarias gariepinus, the African catifish has been illegally introduced for aquaculture in India. It is threatening native catfishes of Indian rivers.

According to Oparin-Haldane theory, life originated through bio-chemical processes of atoms that combined to form molecules. Molecules in turn reacted to produce inorganic and organic compounds. Organic compounds interacted to produce all types of macromolecules which organised to form the first form of life or cells.

Topic in NCERT: Origin of life

Line in NCERT: "oparin of russia and haldane of england proposed that the first form of life could have come from pre-existing non-living organic molecules (e.g. rna, protein, etc.) and that formation of life was preceded by chemical evolution, i.e., formation of diverse organic molecules from inorganic constituents."

Organisms have evolved from simpler forms to complex form. Hence the order of the events are genes first, then heterotrophic prokaryotes, then autotrophic prokaryotes, then eukaryotes and then animals.

Topic in NCERT: Evolution of life forms - a theory

Line in NCERT: Error occcured while getting response from embedding