CBSE Class 9 atomicstructure — practice questions
26 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 9 atomicstructure in the app →Who first proposed in ancient India that matter is made of indivisible particles called parmanus?Cathode rays, discovered by J.J. Thomson in 1897, are streams of:Thomson's 'plum pudding' model of the atom pictured the atom as:The gold foil experiment of Geiger and Marsden (under Rutherford, 1911) used what particles to bombard the foiIn Rutherford's planetary model, the nucleus is approximately how much smaller than the atom?In which year was radioactivity discovered, providing the first evidence that atoms are NOT indivisible?A neutral atom has equal numbers of:Why does the Rutherford model of an atom struggle to explain how electrons can orbit the nucleus indefinitely Which of the following statements correctly orders the historical development of atomic models?The atomic NUMBER of an element equals the number of:The mass NUMBER of an atom equals:Atoms of the same element with different mass numbers (i.e., different numbers of neutrons) are called:For an atom with atomic number 6 (Carbon), the number of electrons in a NEUTRAL atom is:Carbon has two stable isotopes — Carbon-12 (¹²C) with 6 neutrons and Carbon-13 (¹³C) with 7 neutrons. Both havThe MAXIMUM number of electrons that can occupy the second shell (L shell) is:Sodium has 11 electrons. Its electron configuration (electrons in K, L, M shells) is:Chlorine has 17 electrons. To become STABLE (achieve octet in outermost shell), it most easily:The element Fluorine has 9 protons and 10 neutrons. The mass number and atomic number are respectively:An atom of Magnesium loses 2 electrons. The resulting Mg²⁺ ion has the same electron configuration as which noRutherford's gold foil experiment concluded that most of the atom is:Bohr's model of the atom fixed Rutherford's instability problem by proposing that electrons:The neutron was discovered by:The atomic number (Z) of an element is equal to the:An atom of chlorine has atomic number Z = 17 and mass number A = 37. The number of neutrons it contains is:Atoms of the SAME element with DIFFERENT mass numbers are called:Calcium-40 (Z=20, A=40) and Argon-40 (Z=18, A=40) are best described as: