General Science - MCQ Practice Questions
General Science in SSC, railway and state exams stays at school level, which makes it one of the few sections where full marks are realistic. Practice covers physics fundamentals such as motion, light and electricity, chemistry basics including elements and compounds, and biology topics like the human body, nutrition and diseases. Answers stay at the depth the paper actually uses instead of drifting into degree level theory.
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Gas causing global warming?
CO₂ is main greenhouse gas.
Which of the following greenhouse gases has the highest Global Warming Potential (GWP) over a 100-year period?
Understanding:
We need to identify which greenhouse gas has the highest Global Warming Potential (GWP) over a 100-year time horizon among the given options.
Step 1: Define GWP
Global Warming Potential is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific period, relative to carbon dioxide (GWP = 1).
Step 2: Compare GWP values of listed gases
Step 3: Identify the correct answer
Sulphur hexafluoride has by far the highest GWP among the options listed, making it the most potent greenhouse gas per unit mass.
Answer:
Sulphur hexafluoride (SF₆) has the highest Global Warming Potential over a 100-year period among the given options.
Quick Tip:
SF₆ is widely used in electrical switchgear and transformers. Despite being released in small quantities, its extremely high GWP and long atmospheric lifetime make it a significant concern for climate change.
The 'Chipko Movement', which aimed at protecting forests, originated in which Indian state?
Understanding:
We need to identify the Indian state where the Chipko Movement originated.
Step 1: Historical context of the Chipko Movement
The Chipko Movement (meaning 'to hug' or 'to cling') was a non-violent environmental movement in which villagers, especially women, hugged trees to prevent them from being felled by logging contractors.
Step 2: Location of origin
The movement began in 1973 in the Chamoli district of what was then Uttar Pradesh — the region is now part of the state of Uttarakhand (formed in 2000). The key figures associated with the movement include Sundarlal Bahuguna, Gaura Devi, and Chandi Prasad Bhatt.
Step 3: Eliminate other options
Answer:
The Chipko Movement originated in Uttarakhand (formerly part of Uttar Pradesh).
Quick Tip:
The Chipko Movement is considered one of the earliest and most successful grassroots environmental movements in India and inspired similar forest conservation efforts worldwide.
Which layer of the Earth's atmosphere contains the ozone layer that shields the Earth from harmful ultraviolet radiation?
Understanding:
We need to identify the atmospheric layer that contains the ozone layer.
Step 1: Structure of Earth's atmosphere
The atmosphere is divided into layers based on temperature gradients:
Step 2: Location of the ozone layer
The ozone layer is concentrated in the stratosphere, approximately between 15 and 35 km above Earth's surface. Ozone (O₃) in this layer absorbs most of the Sun's harmful ultraviolet (UV-B and UV-C) radiation, preventing it from reaching Earth's surface.
Step 3: Significance
Depletion of the stratospheric ozone layer — caused primarily by chlorofluorocarbons (CFCs) — leads to increased UV radiation reaching Earth, which can cause skin cancer, cataracts, and damage to ecosystems.
Answer:
The ozone layer is found in the stratosphere.
Quick Tip:
Do not confuse stratospheric ozone (beneficial — shields UV) with tropospheric ozone (harmful — a pollutant and component of smog at ground level).
The concept of 'Ecological Footprint' measures which of the following?
Understanding:
We need to identify what the term 'Ecological Footprint' specifically measures.
Step 1: Definition of Ecological Footprint
The Ecological Footprint is a metric developed by Mathis Wackernagel and William Rees in the early 1990s. It quantifies the amount of biologically productive land and water area that a human population requires to produce the resources it consumes and to absorb the waste it generates, using prevailing technology.
Step 2: Eliminate incorrect options
Step 3: Confirm correct answer
The ecological footprint is a comprehensive sustainability indicator encompassing food, water, energy, land for waste absorption, and built-up land — expressed in global hectares (gha).
Answer:
Ecological Footprint measures the biologically productive land and water needed to sustain resource use and absorb waste for a given population.
Which of the following is classified as a 'Hotspot of Biodiversity' in India?
Understanding:
We need to identify which region in India is officially recognised as a Biodiversity Hotspot.
Step 1: What is a Biodiversity Hotspot?
A biodiversity hotspot is a biogeographic region that is both a significant reservoir of biodiversity and is threatened by human habitation. To qualify, a region must have at least 1,500 endemic vascular plant species and have lost at least 70% of its original habitat.
Step 2: India's Biodiversity Hotspots
India has four recognised biodiversity hotspots:
1. Western Ghats
2. Eastern Himalayas (Indo-Burma region)
3. Sundaland (includes Nicobar Islands)
4. Indo-Burma region
Step 3: Evaluate the options
Answer:
The Western Ghats is a recognised Biodiversity Hotspot in India.
Quick Tip:
India hosts 4 of the world's 36 biodiversity hotspots. The Western Ghats alone is home to over 5,000 species of flowering plants, 139 mammal species, 508 bird species, and 179 amphibian species.
Which of the following international agreements specifically deals with the control of trade in endangered species of wild fauna and flora?
Understanding:
We need to match the international agreement that specifically regulates trade in endangered species.
Step 1: Review each agreement
Step 2: Identify the correct agreement
CITES directly addresses the issue of trade in endangered species by listing species in three appendices based on their level of protection needed and controlling or banning their international trade accordingly.
Answer:
CITES is the international agreement that controls trade in endangered species of wild fauna and flora.
Quick Tip:
CITES currently protects over 38,000 species of animals and plants. India is a signatory and has listed species such as tigers, elephants, and rhinos under its provisions.
Eutrophication of water bodies is primarily caused by an excess of which of the following nutrients?
Understanding:
We need to identify the nutrients primarily responsible for eutrophication of water bodies.
Step 1: What is Eutrophication?
Eutrophication is the process by which a water body becomes overly enriched with nutrients, leading to excessive growth of algae and aquatic plants (algal blooms). This reduces dissolved oxygen in the water, creating dead zones and harming aquatic life.
Step 2: Primary nutrients responsible
Nitrogen (N) and Phosphorus (P) are the two key limiting nutrients that trigger eutrophication. They enter water bodies mainly through:
Step 3: Eliminate other options
Answer:
Eutrophication is primarily caused by excess nitrogen and phosphorus in water bodies.
Quick Tip:
The process of oxygen depletion following an algal bloom is called hypoxia. The dead zones formed in water bodies due to eutrophication are well documented in lakes such as Dal Lake (Kashmir) and parts of the Baltic Sea.
Which of the following correctly defines 'Biomagnification'?
Understanding:
We need to identify the correct definition of 'Biomagnification' from the given options.
Step 1: Define Biomagnification
Biomagnification (also called biological magnification or bioamplification) refers to the progressive increase in the concentration of a toxic substance — such as DDT, mercury, or PCBs — in organisms at each successive trophic level of a food chain. The substance is not metabolised or excreted efficiently, so it accumulates in body fat or tissues.
Step 2: Typical example
In the DDT example:
This caused thinning of eggshells in raptors, leading to population declines.
Step 3: Eliminate incorrect options
Answer:
Biomagnification is the increase in concentration of toxic substances at successively higher trophic levels in a food chain.
Quick Tip:
Biomagnification is different from bioaccumulation. Bioaccumulation refers to the build-up of a substance within a single organism, while biomagnification refers to the increase in concentration across trophic levels.
The 'Red Data Book' maintained by the International Union for Conservation of Nature (IUCN) is used for which of the following purposes?
Understanding:
We need to identify the purpose of the IUCN Red Data Book (Red List).
Step 1: What is the IUCN Red List?
The IUCN Red List of Threatened Species (commonly called the Red Data Book) is the world's most comprehensive inventory of the conservation status of biological species. It was established in 1964 and classifies species into categories such as:
Step 2: Purpose
The primary purpose is to document the conservation status of threatened species of plants, animals, fungi, and other organisms to guide conservation efforts and policy decisions globally.
Step 3: Eliminate other options
Answer:
The IUCN Red Data Book documents the conservation status of threatened species of plants, animals, and fungi.
Quick Tip:
As of recent assessments, over 42,000 species are listed as threatened with extinction on the IUCN Red List. India's Great Indian Bustard is listed as Critically Endangered.
Which of the following correctly describes the primary cause of 'Acid Rain'?
Understanding:
We need to identify the primary cause of acid rain from the given options.
Step 1: Chemistry of Acid Rain
Acid rain forms when sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) are released into the atmosphere — mainly from burning fossil fuels, vehicle emissions, and industrial processes. These gases react with water vapour, oxygen, and other chemicals in the atmosphere to form sulphuric acid and nitric acid, which fall as acid rain.
Step 2: Key reactions
The main reactions are:
Step 3: pH of acid rain
Normal rain has a pH of about 5.6 (slightly acidic due to dissolved CO₂ forming carbonic acid). Acid rain has a pH below 5.6, sometimes as low as 4 or less.
Step 4: Eliminate incorrect options
Answer:
Acid rain is primarily caused by emissions of sulphur dioxide and nitrogen oxides that react with atmospheric moisture to form sulphuric and nitric acids.
Quick Tip:
Acid rain causes damage to forests, aquatic ecosystems, soil, and heritage structures (such as the Taj Mahal, which has been affected by acid rain from nearby industries).