Population Density

Correct answer: A. Density = population ÷ area; it shows the average concentration of people

Correct answer: A — population density is population divided by area, usually expressed as people per square kilometre. First identify the two quantities: the number of people and the land area in which they live. Dividing the population by the area gives the average number of people occupying each unit of area. For example, 1,000 people living in 10 square kilometres gives a density of 100 people per square kilometre. Option B reverses the formula and does not measure birth rate; birth rate concerns births during a period. Option C uses weather elements and has no connection with demographic density. Option D combines social characteristics, not population and area. Remember: density asks ‘how many people in how much space?’ It is an average and may hide differences between crowded and sparsely settled localities.

Correct answer: A. On average, there are 1,000 people in each square kilometre

Correct answer: A. Population density tells us how many people live, on average, in a unit of area. The formula is density = total population ÷ total area. Therefore, 1,000 persons per square kilometre means that the average number of people is 1,000 for every square kilometre. The word “average” matters: the people may not be spread evenly, because some parts can be more crowded and others less crowded. B is wrong because 1,000 is a rate per square kilometre, not necessarily the total population. If the area were 5 square kilometres at the same average density, its population would be about 5,000. C reverses the relationship and gives the wrong unit. D is wrong because the density value does not itself tell us the total area. Memory cue: density = people ÷ area; always read the unit.

Correct answer: A. How concentrated people are and where they are spread

Correct answer: A. Population density and population distribution are related but different ideas. Density measures the number of people in a unit of area, while distribution describes where people live and whether they are clustered, evenly spread, or absent from particular places. Studying both gives a fuller spatial picture. Two regions may have the same average density, yet one may have people spread fairly evenly while the other may have a crowded city and a sparsely populated countryside. A is correct because it includes both the amount of concentration and the location pattern. B concerns births, not spatial settlement. C concerns weather, which may influence settlement but is not the combined meaning. D concerns language composition, not density and distribution. Memory cue: density answers “how many per area?” and distribution answers “where?”

Correct answer: B. Seven hundred fifty persons per square kilometre

Direct answer: Option B, 750 persons per square kilometre. Population density means the number of people living in one square kilometre. Use the formula: density = population ÷ area. Eighteen lakh means 1,800,000 people. Now calculate 1,800,000 ÷ 2,400. Since 2,400 × 750 = 1,800,000, the density is 750 persons per square kilometre. Option A would result from an incorrect division and is too low. Option C is incorrect because 2,400 × 900 equals 2,160,000, not 1,800,000. Option D is also incorrect because 2,400 × 1,200 equals 2,880,000. Always retain the unit: persons per square kilometre. A helpful check is to multiply the proposed answer by the area; the product must equal the population.

Correct answer: B. Eight hundred persons per square kilometre

Direct answer: Option B, 800 persons per square kilometre. Apply the formula density = population ÷ area. Twenty-four lakh is 2,400,000 people, and the area is 3,000 square kilometres. Divide: 2,400,000 ÷ 3,000 = 800. A quick verification is 800 × 3,000 = 2,400,000. Option A is wrong because 600 × 3,000 gives only 1,800,000. Option C is wrong because 1,000 × 3,000 gives 3,000,000. Option D is wrong because 1,200 × 3,000 gives 3,600,000. The final unit must be persons per square kilometre, not simply persons or square kilometres. A useful calculation habit is to cancel three zeros first: 2,400,000 ÷ 3,000 becomes 2,400 ÷ 3, which equals 800.

Correct answer: D. Transport and connectivity facilities

Correct answer: D, transport and connectivity facilities. Population density means the number of people living in one unit of area, usually one square kilometre. A good road makes travel easier and connects residents with markets, schools, hospitals, workplaces and other services. Because access improves, workers, traders and families may be attracted to the area, or people already living there may be able to settle more permanently. Thus transport can influence where people live and can raise density over time. A is incorrect because rainfall may influence farming and settlement, but the question directly points to a road. B is incorrect because soil colour alone does not explain improved access or movement. C is incorrect because an area does not become zero when a road is built. Memory cue: better roads often mean better access, and better access can attract people; density is people divided by area.

Correct answer: A. Public health risk

Correct answer: A, public health risk. Very high density means many people live in a relatively small area. If sanitation is weak, wastewater, solid waste and human waste may not be safely removed. Crowded living conditions can then make it easier for infections to spread, especially when clean water and hygiene facilities are also insufficient. This does not mean every dense area is unhealthy; good planning and sanitation can reduce the danger. B is incorrect because poor sanitation does not enlarge the physical area. C is unrelated to population density and sanitation. D is incorrect because weak sanitation does not make the population automatically disappear. The key chain is: high density plus weak sanitation can increase exposure and disease risk. Memory cue: density describes crowding, while sanitation describes safe waste and hygiene management; together they affect public health.

Correct answer: B. Eight hundred persons per square kilometre

Correct answer: B, eight hundred persons per square kilometre. Population density is calculated by dividing total population by total area. Thirty-six lakh means 3,600,000 people. Therefore, density = 3,600,000 ÷ 4,500 = 800 persons per square kilometre. The unit is important because the answer tells us how many people, on average, live in each square kilometre. A gives 600, which would result from an incorrect division. C gives 900, and D gives 1,000; neither matches the stated numbers. A safe method is to cancel zeros carefully or check the result by multiplication: 800 × 4,500 = 3,600,000. Do not divide area by population, because that reverses the meaning of density. Memory cue: density equals people divided by land area, not land area divided by people.

Correct answer: A. Five thousand square kilometres

Correct answer: A, five thousand square kilometres. The basic formula is density = population ÷ area. When area is required, rearrange it as area = population ÷ density. Fifty lakh equals 5,000,000 people, and the density is 1,000 persons per square kilometre. Therefore, area = 5,000,000 ÷ 1,000 = 5,000 square kilometres. The unit is square kilometres because the question gives density per square kilometre. B is too small and would correspond to a different division. C is ten times the correct result, and D also does not satisfy the formula. Check the answer by multiplying: 5,000 square kilometres × 1,000 persons per square kilometre = 5,000,000 persons. Memory cue: if population and density are known, divide population by density to find area.

Correct answer: A. Density can become four times

Answer: A, density can become four times. Population density means the number of people living in one unit of area, usually one square kilometre. The formula is density = population ÷ area. Here the population does not change, but the area becomes one-fourth of its original size. Dividing the same population by a smaller area makes the density larger. For example, if 400 people live in 4 square kilometres, density is 100 people per square kilometre. If the same 400 people occupy only 1 square kilometre, density becomes 400 people per square kilometre, which is four times the original density. Option A is correct. B is wrong because density does not decrease when the area becomes smaller. C is wrong because the people have not disappeared. D is wrong because the denominator in the formula has changed. Memory cue: same people in less space means greater crowding; one-fourth area means four times density.

Correct answer: A. Density will become half

Answer: A, density will become half. Use density = population ÷ area. Let the original population be P and the original area be S. Original density is P/S. The new population is 2P and the new area is 4S, so new density is 2P ÷ 4S = P/(2S), which is half of the original density. The population has increased, but the area has increased twice as much in relative terms. Option A is therefore correct. B is wrong because it considers the doubling of population but ignores the fourfold increase in area. C is wrong because the area, not density, becomes four times. D is wrong because the two changes do not balance: doubling the numerator and quadrupling the denominator reduces the result by half. A useful method is to compare multipliers: new density factor = population factor ÷ area factor = 2 ÷ 4 = 1/2. Memory cue: if area grows faster than population, density falls.

Correct answer: B. Five hundred persons per square kilometre

Answer: B, 500 persons per square kilometre. Population density is calculated by dividing population by area. In the Indian numbering system, thirty-two lakh means 3,200,000 people. Now calculate: 3,200,000 ÷ 6,400. Since 6,400 × 500 = 3,200,000, the density is 500 persons per square kilometre. Another quick method is to write 32 lakh as 320 ten-thousands and divide by 6,400; the same result is obtained. Option B is correct. Option A would result from an incorrect division or from using the wrong area. Option C is too high because 6,400 × 800 would give 5,120,000 people, not 3,200,000. Option D is also too high because 6,400 × 1,000 would give 6,400,000 people. Always include the unit persons per square kilometre. Memory cue: density is people divided by land area, not area divided by people.

Correct answer: B. Six hundred persons per square kilometre

Correct answer: B, six hundred persons per square kilometre. Population density is calculated by dividing total population by total area: density = population ÷ area. Forty-eight lakh means 4,800,000 people. Now divide 4,800,000 by 8,000. Cancelling three zeros gives 4,800 ÷ 8 = 600. Therefore, the density is 600 persons per square kilometre. A is wrong because 400 would result from an incorrect division. C is wrong because it overestimates the quotient; 8,000 multiplied by 800 would equal 6,400,000, not 4,800,000. D is also too high; 8,000 multiplied by 1,200 would equal 9,600,000. Always include the unit because density is not just a number. Memory cue: population on top, area below: people ÷ square kilometres.

Correct answer: A. Because it is linked with people removed from the population through deaths

Direct answer: A. Death rate measures deaths in a population during a stated period, often in relation to the population size. Deaths reduce the number of people, so death rate must be considered when studying population growth. The basic relationship is natural increase = births minus deaths. Thus, if births stay the same, a higher death rate usually makes natural increase smaller; a lower death rate usually allows greater natural increase. A is correct because it refers to people leaving the population through death. B is wrong because language counts describe cultural composition, not mortality. C concerns roads, and D concerns neither demography nor measurement of population change. The word “removed” here means lost through death, not physically taken away.

Correct answer: B. People going out of an area

The direct answer is B: people going out of an area. Emigration means movement away from the country, region or area being considered, generally to live elsewhere. First identify the reference place and then observe the direction: outward movement from that place is emigration. Option B is correct because it describes this outward movement. Option A is wrong because people entering a place are immigrants there; that is immigration, the opposite direction. Option C is wrong because birth rate measures births and does not describe movement across a boundary. Option D is wrong because a lower death rate concerns mortality and survival, not migration. A single move can be described in both ways depending on viewpoint: the person emigrates from the old place and immigrates to the new place. Memory cue: emigration is exit or moving out.

Correct answer: C. Two per thousand

Direct answer: C, two per thousand. Natural increase measures the excess of births over deaths, so use the formula birth rate minus death rate. Here, 10 per thousand − 8 per thousand = 2 per thousand. A is wrong because it adds births and deaths; deaths reduce natural increase rather than increase it. B is only the death rate, not the difference between births and deaths. D is only the birth rate and ignores the people who die. Migration is not included in natural increase; it would be considered separately when calculating total population change. Memory cue: natural increase = B − D, where B means births and D means deaths. Keep the unit unchanged: since both given rates are per thousand, the answer is also per thousand.

Correct answer: A. Movement of people from one place to another

The direct answer is A: migration is the movement of people from one place to another. People may move within the same country or across an international boundary, and the movement may be temporary or permanent. The essential idea is a change of usual residence or place by people. Option A is correct because it directly describes human movement. Option B describes evaporation, in which liquid water changes into water vapour; it is part of the water cycle, not migration. Option C describes erosion, in which moving water wears away and carries soil or rock. Option D describes mountain formation, a geological process involving changes in the Earth’s crust. None of these three processes refers to people changing their place. Migration can affect the population of both the place people leave and the place where they arrive. Memory cue: migration means people move; evaporation means water changes state.

Correct answer: B. The population may increase

The direct answer is B: in-migration may increase the population of an area. In-migration means that people enter an area from another place and settle or stay there. These people are added to the receiving area’s population. For example, if a town has 10,000 residents and 500 people move into it, the population can rise to 10,500 if no other change is considered. Option A is wrong because a decrease is more directly associated with out-migration, although the final total can depend on births and deaths too. Option B is correct because incoming people add to the population. Option C is wrong because the entry of people is a population change, not an absence of change. Option D is wrong because migration changes the number of people, not the physical area of the land. Memory cue: in means inwards; in-migration brings people in and usually raises population.

Correct answer: A. 300

Correct answer: A, 300. Natural increase measures the change caused only by births and deaths, so migration is not included. The rule is natural increase = births − deaths. Substitute the values: 800 − 500 = 300. Because births are greater than deaths, the answer is positive, meaning the population has increased naturally by 300 people. Option B is only the number of deaths and does not show the difference. Option C is only the number of births. Option D comes from adding births and deaths, but natural increase requires subtraction, not addition. If deaths had been greater than births, the result would have been negative. Memory cue: for natural increase, start with births and subtract deaths.

Correct answer: B. When the area remains the same and the population increases

The correct answer is B: when the area remains the same and the population increases. Population density tells us how many people live in a unit of area, commonly people per square kilometre. The formula is density = population ÷ area. If the area remains fixed, any increase in population directly raises the density. For example, 1,000 people in 10 square kilometres gives 100 people per square kilometre; if the population becomes 2,000 while the area stays 10 square kilometres, density becomes 200. A is less clear because a rapidly increasing area can offset some population increase. C generally lowers density if area is unchanged. D gives zero density, not an effect of population growth. Memory cue: fixed denominator plus a larger numerator means a larger density.