General Science/Everyday Science MCQs
Topic Notes: General Science/Everyday Science
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
141
The 'shielding effect' (or screening effect) refers to:
Answer:
The repulsion of inner shell electrons on valence electrons
Inner shell electrons act as a 'shield' between the positive nucleus and the valence electrons, reducing the effective nuclear charge felt by the outermost electrons. This effect increases as the number of occupied inner shells increases down a group.
142
What is the relative mass of an electron compared to a proton?
Answer:
Approximately 1/1840
Electrons are much lighter than protons and neutrons. It takes about 1836 to 1840 electrons to equal the mass of a single proton.
143
What does the 'Cold Chain' refer to in the distribution of vaccines?
Answer:
A system of storing and transporting vaccines at specific cold temperatures to keep them effective
Most vaccines are biological products that break down if they get too warm. The 'cold chain' is a series of refrigerators, coolers, and monitoring tools used from the factory to the clinic to ensure the vaccine remains potent and safe.
144
Which of the following elements is a 'Noble Metal' due to its low reactivity?
Answer:
Gold
Noble metals (like Gold, Platinum, and Silver) are resistant to corrosion and oxidation in moist air, unlike base metals like Iron or Sodium.
145
Some antibiotics target the 70S ribosomes in bacteria. Why does this usually not harm the human host?
Answer:
Human cells have different 80S ribosomes that the antibiotic does not recognize
One of the reasons antibiotics are 'selectively toxic' is that prokaryotic (bacterial) ribosomes are structurally different from eukaryotic (human) ribosomes. This allows the drug to stop protein synthesis in the bacteria without affecting the host's ability to make proteins.
146
Second ionization energy is always _______ than the first ionization energy.
Answer:
Greater
Removing a second electron requires pulling it away from a positively charged ion ($X^+$). The remaining electrons feel a stronger effective nuclear charge and are held more tightly, requiring significantly more energy.
147
Which of the following practices is the most effective way to prevent the transmission of many infectious diseases in daily life?
Answer:
Regular handwashing with soap and water
Handwashing is the single most effective way to remove pathogens from the hands before they can enter the body through the mouth, nose, or eyes, or be passed on to other people and surfaces.
148
What is the function of an 'Adjuvant' which is often added to some vaccines?
Answer:
To enhance the body's immune response to the vaccine
Adjuvants are substances added to vaccines to boost the immune response. They help the body produce more antibodies and longer-lasting immunity, which is particularly useful for vaccines that use 'dead' or subunit antigens that might otherwise be too weak.
149
What is the primary danger of using antibiotics to treat 'viral' sore throats?
Answer:
It contributes to the global problem of antibiotic resistance without helping the patient
Most sore throats are viral. Taking antibiotics for them doesn't kill the virus but does expose the 'good' and 'bystander' bacteria in your body to the drug. This gives those bacteria a chance to develop resistance, which they can later pass on to dangerous pathogens.
150
Who discovered the neutron?
Answer:
James Chadwick
James Chadwick discovered the neutron in 1932. This discovery was crucial because it explained why the atomic mass of elements was often more than double their atomic number.