Dear Students and Respected Teachers! These are up-to-date papers for Chemistry-10th for all Punjab boards. These include 2018 to 2024 past papers of all nine educational boards of Punjab. These are PDFs of all these past papers in descending annual…
Dear Students and Respected Teachers! These are 9th class up-to-date papers for Chemistry for all Punjab boards. These are six year past papers from 2018 to 2024 for nine educational boards of Punjab. Here are the PDFs of all these…
ANSWER: Molar mass of urea = 14+2+12+16+14+2 = 60 g Mass of N in the molecule = 28 g % of N = Mass of N / Molar Mass ✕ 100 = 28 gmol-1 / 60 gmol-1 ✕ 100 =…
ANSWER: QUALITATIVE ANALYSIS In qualitative analysis, the elements present in a compound are identified. QUANTITATIVE ANALYSIS In quantitative analysis, the relative amount of each element in a compound is determined. (Ref. An Insight Into Objective Chemsitry-11, Ch-01, Q. No. 29)
ANSWER: In mass spectrum, the number of peaks tells about the number of isotopes, while the heights of the peaks represent their natural abundance. Two equally strong peaks in the mass spectrum of bromine indicate that bromine has two isotopes…
ANSWER: Neon has three isotopes Ne–20, Ne–21 & Ne–22, having percentage abundance of 90.92%, 0.26% & 8.82% respectively. When we calculate average of all these isotopic masses in proportion to their natural abundances, a fractional value of 20.18 amu is…
ANSWER: Most of the elements have fractional atomic masses. This is because most elements have isotopes, each with different natural abundance. The atomic mass is actually the average of all the isotopic masses, proportional to their relative abundance. So, their…
ANSWER: Methods for the Separation of Isotopes: Isotopes have different physical properties, so they can be separated by the methods based on these properties. Some of these methods are: 1) Gaseous diffusion 2) Thermal diffusion 3) Electromagnetic separation 4) Laser…
ANSWER: Function of Electrometer: The electrometer collects the positive ions and develops the electric current. The strength of the current gives the relative abundance of the isotope. (Ref. An Insight Into Objective Chemsitry-11, Ch-01, Q. No. 25)
ANSWER: Function of Magnetic Field: When an accelerated beam of isotopic positive ions is allowed to pass through a strong magnetic field, the field makes them move in a circular path. The ions are, thus, separated on the basis of…