11.2L/22.4L (STP value) x 1 mol of CH4 x 16.04 g of CH4 = 8.2 g
Elements present in group 18 are known as noble gases. The outermost shell of these elements are completely filled.
18 is the answer
Explanations:- As per the significant figures rule, In multiplication and division, we go with least number of sig figs.
4.03 has three sig figs where as 0.0000035 has two sig figs only, The zeros in this number are not sig figs as they are just holding the place values. As the least number of sig figs here is two, the answer needs to be reported with two sig figs only.

Answer:
B. PhCHO
Explanation:
Every organic group shows a characteristic IR absorption at certain wavelength . With the help of these absorption spectra we can identify the group present on organic molecules .
The wave number of 2710 cm⁻¹ is absorbed by aldehyde bond stretching .
The wave number of 1705 cm⁻¹ is shown by conjugated aldehyde . So the most likely compound among given compounds is PhCHO .
A 0.12 M solution of an acid that only slightly ionizes in solution would be termed a weak acid. Weak acids are acids which do not completely dissociate in water. Thus lowering the presence of hydronium ions which measures the pH of an acid. <span />