MCQ Structure of the Atom Chapter 4 Class 9 Science Advertisement MCQ’s For All Chapters – Science Class 9th 1. What happens to an atom when it loses one electron?Becomes negatively chargedBecomes positively chargedBecomes neutralBecomes unstable isotopeQuestion 1 of 202. The element with configuration 2,8,7 belongs to which group?Alkali metalsNoble gasesHalogensAlkaline earth metalsQuestion 2 of 203. The isotope used in treatment of cancer isIodine-131Uranium-235Cobalt-60Hydrogen-3Question 3 of 204. If K and L shells are full, how many electrons are there?8101820Question 4 of 205. The number of electrons in sulphur atom (atomic number 16) is816326Question 5 of 206. Which one of the following is true about isotopes of chlorine?Different atomic numberSame mass numberDifferent neutronsSame number of neutronsQuestion 6 of 207. The electronic configuration of neon is2,62,82,8,12,7Question 7 of 208. The maximum number of electrons in N shell is18243240Question 8 of 209. What is the relation between atomic number and number of electrons in a neutral atom?Atomic number = neutronsAtomic number = protonsAtomic number = electronsBoth B and CQuestion 9 of 2010. The mass number of oxygen is 16 and atomic number is 8.Its number of neutrons is8162432Question 10 of 2011. The electron distribution of phosphorus (Z=15) is2,8,52,7,62,8,82,8,3Question 11 of 2012. Which of the following atoms has a stable electronic configuration?SodiumNeonAluminiumOxygenQuestion 12 of 2013. An element X forms an ion X²⁻ with configuration 2,8.What is atomic number of X?8101214Question 13 of 2014. Which scientist discovered the nucleus?BohrRutherfordThomsonGoldsteinQuestion 14 of 2015. What was the main observation in Rutherford’s experiment?All α-particles bounced backMost passed straight through foilNone passed through foilAll deflected at large anglesQuestion 15 of 2016. Which one of the following is correct for a neutral atom of fluorine?9 protons, 9 electrons9 protons, 10 electrons9 neutrons, 9 protons10 neutrons, 9 electronsQuestion 16 of 2017. If the ratio of chlorine isotopes (³⁵Cl:³⁷Cl) is 3:1, what percentage of ³⁷Cl is present?25%30%35%50%Question 17 of 2018. The average atomic mass of bromine with 79Br (49.7%) and 81Br (50.3%) is approximately80.080.681.079.3Question 18 of 2019. Which postulate of Bohr’s model explains atomic stability?Electrons radiate energy in orbitElectrons occupy discrete energy levelsNucleus contains neutronsElectron paths are randomQuestion 19 of 2020. The number of protons in ³⁷₁₇Cl is17203718Question 20 of 20 Loading...
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