General Science Questions (MCQs) for Competitive Examinations
General Science Multiple choice questions for GK paper in SSC, NDA, CDS, UPSC, UPPSC and State PSC Examinations. These questions are part of GKToday’s 35000+ MCQs Bank Course in GKToday Android App
1. Which iron ore contains the highest percentage of iron content?
[A] Hematite
[B] Siderite
[C] Magnetite
[D] Limonite
Show Answer
Correct Answer: C [Magnetite]
Notes:
Magnetite (Fe3O4) typically contains about 70% iron by weight. It is black in color and strongly magnetic. Hematite (Fe2O3) contains about 60–70% iron. Limonite contains 35–50% iron. Siderite (FeCO3) contains about 48% iron. Magnetite is widely mined due to its high iron concentration compared to other ores.
2. As per the Mohs scale of mineral hardness, which of the following are soft metals?
- Gold
- Copper
- Diamond
- Thorium
Select the correct option from codes given below:
[A] 1 & 4 Only
[B] 1, 2 & 4 Only
[C] 2 & 4 Only
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: B [ 1, 2 & 4 Only]
Notes:
As per the Mohs scale of mineral hardness, the soft metals are: Lead, gold, silver, tin, zinc, aluminium, thorium, copper, brass and bronze. Diamond is one of the hardest known metals on earth.
3. The biological process in which both aerobes and anaerobes degrade organic matter is ____:
[A] Digesting
[B] Composting
[C] Manuring
[D] Nutrifying
Show Answer
Correct Answer: B [Composting]
Notes:
Composting is the depomposition of plant remains and other once-living materials to make an earthy, dark, crumbly substance that is excellent for enriching soil. It is the chief way to recycle wastes.
4. Wilting of plants occurs due to excessive ____:
[A] Respiration
[B] Glutation
[C] Absorption
[D] Transpiration
Show Answer
Correct Answer: D [Transpiration]
Notes:
Plant wilting occurs after excessive loss of water by transpiration and lesser absorption. i.e. rate of transpiration exceeds rate of water absorption. On a hot day, plants transpire heavily and cannot absorb water speedily to keep pace with transpiration loss, even when there is enough water.
5. Which of the following diseases has been eradicated worldwide?
[A] Smallpox
[B] Plague
[C] Chickenpox
[D] Dracunculiasis
Show Answer
Correct Answer: A [Smallpox]
Notes:
Smallpox was one of the world’s most devastating diseases known to humanity. The last known natural case was in Somalia in 1977. It was declared eradicated in 1980 following a global immunization campaign led by the World Health Organization. Smallpox is caused by infection with the variola virus.
6. The pigment that gives human skin, hair and eyes their colour is called ____:
[A] Quinacridone
[B] Alizarin
[C] Melanin
[D] Phthalocyanine
Show Answer
Correct Answer: C [Melanin ]
Notes:
The pigment that gives human skin, hair, and eyes their color. Dark-skinned people have more melanin in their skin than light-skinned people have. Melanin is produced by cells called melanocytes. Everyone has the same number of melanocytes, but some people make more melanin than others.
7. The colour change in the Chameleon is due to the presence of ____:
[A] Chromatophore
[B] Haemoglobin
[C] Chlorophyll
[D] Pneumatophore
Show Answer
Correct Answer: A [Chromatophore]
Notes:
Chameleons have specialized cells, chromatophores, which contain pigments in their cytoplasm, in three layers below their transparent outer skin. Dispersion of the pigment granules in the chromatophores sets the intensity of each color. Chromatophores contain pigments and reflect light, which are responsible for creating coloration. In chameleons, there are four types of chromatophores: xanthophores, erythrophores, iridiophores, and melanophores (Cooper and Greenberg, 1992).
8. Cuscuta is a ____:
[A] Complete stem parasite
[B] Partial root parasite
[C] Partial stem parasite
[D] Complete root parasite
Show Answer
Correct Answer: A [Complete stem parasite]
Notes:
Cuscuta (Dodder) is a genus of about 100-170 species of yellow, orange or red (rarely green) parasitic plants. Dodders are supremely adapted for a life of plunder and pillage. Reduced in form to scrambling and twining threads, they appear to be completely leafless, although closer inspection reveals tiny scale leaves pressed close to the stems. So, it is a stem parasite.
9. Fat present below the skin surface in our body acts as a barrier against ____:
[A] Loss of heat from the body
[B] Loss of salt from the body
[C] Loss of essential body fluids
[D] Entry of harmful micro-organisms from the environment
Show Answer
Correct Answer: A [Loss of heat from the body]
Notes:
A layer of body fat acts as an insulator and traps heat. The subcutis is the deepest layer of skin. The subcutis, consisting of a network of collagen and fat cells, helps conserve the body’s heat and protects the body from injury by acting as a “shock absorber.
10. Biodegradable wastes can usually be converted into useful substances with the help of ____:
[A] Bacteria
[B] Viruses
[C] Nuclear proteins
[D] Radioactive substances
Show Answer
Correct Answer: A [Bacteria]
Notes:
Bacteria are the most abundant organisms which play important role in the decomposition of organic matter. Majority of bacteria involved in decomposition of organic matter are heterotrophs and autotrophs are least in proportion which are not directly involved in organic matter decomposition.
