The correct answer is (d)(i), (ii) and (iv). Dalton’s atomic theory successfully explained: Law of Conservation of Mass(i) – Atoms are neither created nor destroyed in a chemical reaction. Law of Constant Composition(ii) – A compound always contains the same ...
Discussion Forum Latest Questions
The correct answer is (b) 2,8,2. Magnesium (Mg) has an atomic number of 12, meaning it has 12 electrons. The electronic distribution follows the 2,8,2 pattern according to the Bohr model, where the first shell holds 2 electrons, the second ...
The correct answer is (c) different neutrons. Isotopes of an element have the same number of protons and electrons but different numbers of neutrons. This results in the same chemical properties but slightly different physical properties, such as mass and ...
The correct answer is (a) An atom has an equal number of electrons and protons. Atoms are electrically neutral, meaning the number of protons (positively charged) always equals the number of electrons (negatively charged). However, the number of neutrons may ...
The correct answer is (c) The two oxygen atoms are isotopes. Isotopes of an element have the same number of electrons and protons but different numbers of neutrons. In ethyl ethanoate (CH₃COOC₂H₅), both oxygen atoms belong to the same element ...
Non-metals like fluorine (F), chlorine (Cl), and bromine (Br), which gain one electron to form negative ions (anions). Thus, elements with valency 1 are not always metals or non-metals but can be either. Class 9th Science NCERT MCQ Questions NCERT ...
The correct answer is: (c) either metals or non-metals. Elements with valency 1 can be: Metals like sodium (Na), potassium (K), and lithium (Li), which lose one electron to form positive ions (cations). Class 9th Science NCERT MCQ Questions NCERT ...
The atom with 3 protons is lithium (Li) because its atomic number is 3. The electronic configuration of lithium is 2,1, meaning it has one valence electron in its outermost shell. Valency is the number of electrons an atom loses, ...
The atomic number of aluminium is 13, meaning it has 13 electrons. The electrons are arranged in shells following the 2, 8, 3 distribution: 2 electrons in the first shell, 8 in the second, and 3 in the third. So, ...
The correct answer is:(c) nucleus in the atom Rutherford’s α-particle scattering experiment demonstrated that the positive charge and most of the mass of an atom are concentrated in a small central nucleus. This led to the discovery of the atomic ...