Chemistry - Study Mode
[#206] The number of neutrons present in an element having mass number 226 and atomic number 88 is :
Correct Answer
(B) 138
Explanation
Solution: The mass number is a count of the number of particles in an atom's nucleus which is made up of protons and neutrons. In other words, Mass Number = Number of Protons + Number of Neutrons. The atomic number is the number of protons in an atom of an element, i.e., 226 = 88 + number of Neutrons. So, the number of neutrons= 226 – 88= 138.
[#207] Who modified Bohr's theory by introducing elliptical orbits for electron path?
Correct Answer
(D) Sommerfeld
Explanation
Solution: Sommerfeld modified Bohr's theory. According to him electrons move in elliptical orbits in addition to circular orbits.
[#208] Which of the following compounds is commonly used as an antiseptic in mouthwashes and toothpastes ?
Correct Answer
(D) Sodium chloride
Explanation
Solution: Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter’s ability to be transported through the lymphatic system to destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects. Some antiseptics are true germicides, capable of destroying microbes (bacteriocidal), while others are bacteriostatic and only prevent or inhibit their growth. Antibacterials are antiseptics that have the proven ability to act against bacteria. Microbicides which destroy virus particles are called viricides or antivirals. Sodium chloride,Used as a general cleanser. It is also used as an antiseptic mouthwash.
[#209] Soap is prepared by boiling caustic soda with
Correct Answer
(D) Fats
Explanation
Solution: The most basic kind of soap is made from caustic soda and animal fat. The two are heated together, and then cooled. The process is called “saponification”. In technical terms, saponification involves base (usually caustic soda NaOH) hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate.
[#210] 'All the four quantum numbers of two electrons in an atom are not the same.' It is the law of –
Correct Answer
(B) Exclusion Principle of Pauli
Explanation
Solution: The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.