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
71
Which scientist is credited with arranging the elements in 'Triads' based on their similar properties?
Answer:
Johann Döbereiner
Döbereiner's Law of Triads (1817) suggested that groups of three elements shared similar properties, and the atomic mass of the middle element was approximately the average of the other two, such as Lithium, Sodium, and Potassium.
72
Atomic volume generally _______ down a group.
Answer:
Increases
As we move down a group, the addition of new electron shells outweighs the increase in nuclear charge, causing the overall volume of the atom to increase.
73
The total number of protons and neutrons in an atom is known as the:
Answer:
Mass number
The mass number ($A$) is the sum of the number of protons ($Z$) and the number of neutrons ($N$) in the nucleus. It represents the approximate mass of the atom in atomic mass units (amu).
74
In the Bohr model of the atom, electrons move in:
Answer:
Fixed circular orbits
Niels Bohr proposed that electrons circle the nucleus in prescribed orbits of fixed energy. Electrons can jump between these levels by absorbing or emitting specific amounts of energy (quanta).
75
Across a period from left to right, the atomic radius generally:
Answer:
Decreases
As we move across a period, the atomic number increases, meaning more protons are added to the nucleus. This increases the effective nuclear charge, which pulls the electron shells closer to the nucleus, resulting in a smaller atomic radius.
76
Which subatomic particle carries a negative electric charge?
Answer:
Electron
Electrons are subatomic particles with a negative elementary charge. They orbit the nucleus of an atom in specific energy levels or shells and are involved in chemical bonding and electricity.
77
Which of the following is true for a neutral atom of Carbon-14?
Answer:
It has 6 protons and 8 neutrons
Carbon always has an atomic number of 6 (6 protons). In Carbon-14, the mass number is 14. Therefore, the number of neutrons is $14 - 6 = 8$.
78
In the symbol $^{23}_{11}Na$, what does the number 23 represent?
Answer:
The mass number
In standard nuclear notation, the superscript represents the mass number ($A$), which is the sum of protons and neutrons. The subscript represents the atomic number ($Z$).
79
Elements of Group 1 are collectively called:
Answer:
Alkali Metals
Group 1 elements (excluding Hydrogen) are called Alkali Metals because they react with water to form strong alkaline hydroxides. They have one valence electron ($ns^1$) and are highly reactive.
80
Which block of the Periodic Table contains the Transition Elements?
Answer:
d-block
The d-block consists of elements in Groups 3 to 12. They are called transition elements because they represent a transition in properties between the highly reactive metals of the s-block and the non-metals of the p-block.