← Back to Chapter
Important:
नीचे दिए गए year-wise links official CBSE question-paper
pages पर ले जाते हैं। Chapter-specific questions को
अलग से “Official Chapter Practice” में रखा गया है ताकि
किसी practice question को गलत तरीके से previous-year
question न बताया जाए.
Official CBSE Previous Year Papers
Official Chapter Practice
CBSE Competency-Based Practice
An assertion says that atomic size increases from left to right
across a period. Is the assertion correct? Explain using the
relevant periodic trend.
The assertion is incorrect. Atomic size generally decreases
from left to right across a period because nuclear attraction
increases while electrons are added to the same principal shell.
Source: CBSE official competency-focused Science material.
CBSE Competency-Based Practice
An isotope of hydrogen is considered for placement in the
periodic table. Explain whether an isotope should receive a
separate position.
Isotopes have the same atomic number and therefore occupy the
same position in the modern periodic table. Their different
mass numbers do not give them separate positions.
Source: CBSE official Science competency-focused material.
CBSE Competency-Based Practice
What conclusion can be drawn about electronegativity across
the first three periods from the supplied periodic data?
Electronegativity generally increases across a period as the
effective nuclear attraction for shared electrons increases.
The exact trend should be interpreted using the supplied
values and the position of the elements.
Source: CBSE official competency-focused Science material.
CBSE Official Practice
Two elements are in the same period and have the same valency.
If one experiences stronger attraction between the nucleus and
its valence electrons, what trend-related difference is
expected?
The element experiencing stronger attraction is expected to
have a smaller atomic radius. Such differences can also relate
to metallic character and electronegativity.
Source: CBSE official Science competency-focused material.
CBSE Official Practice
An element's position in the periodic table is used to infer
properties such as size, valency and metallic character.
Why is position useful for this purpose?
Position reflects the atomic number and electronic arrangement
of the element. These factors determine recurring periodic
trends and therefore help predict chemical behaviour.
Source: CBSE official curriculum-aligned competency material.
More Official Practice