Explanation

When the 6d orbital is completely filled, the next electron enters the 7p orbital.

This is based on the Aufbau principle, which dictates that electrons first occupy the lowest energy levels available.

After the 6d orbitals (which can hold up to 10 electrons) are filled, 

The 7p orbitals (which can hold up to 6 electrons) become the next lowest energy

Explanation

Volume of a sphere (or similar 3D object):

V= 4/3​πr^3

• So, volume depends on the cube of the radius.

• Percentage error in volume = 3 × (percentage error in radius)

$$\text{Error in volume}=3\times 1\%=3\%$$

Explanation

Within the ovule of Pinus, a megaspore mother cell undergoes meiosis, resulting in the production of four haploid megaspores.

However, only one of these megaspores survives and develops into the female gametophyte. 

Explanation

The Pfund series of hydrogen spectral lines occurs when electrons fall to the n = 5 energy level from higher levels.

These transitions emit radiation in the infrared (IR) region of the electromagnetic spectrum.

Explanation

Aluminum sulphate (also called alum) is a common coagulant used to purify potable water by causing suspended impurities to clump together and settle.

It helps remove particles, bacteria, and organic matter by forming flocs during the coagulation-flocculation process.

Explanation

The action "when I saw him" is in the past, so the ongoing past action should use past continuous tense.

"Was learning" correctly matches the timing and form.

Explanation

Eukaryotic ribosomes are made of two subunits: 60S (large) and 40S (small), combining to form the 80S ribosome.

The "S" stands for Svedberg unit, a measure of sedimentation rate during centrifugation.

Explanation

Deliberately means جان بوجھ کر یا مقصد کے مطابق کچھ کرنا ، حادثے سے نہیں

Purposely means منصوبہ بند یا شعوری عمل کے خیال کو پہنچانا

Explanation

An Ogive is a graph that shows cumulative frequencies, either less than or greater than a certain class limit.

It's used to determine medians, percentiles, and quartiles visually.

Explanation

r is the carriage return escape sequence, which moves the cursor to the beginning of the current line.

It does not move to the next line, unlike n (newline).