ICSE Class 11 Chemistry — Important Questions

According to Avogadro's hypothesis, under identical conditions of temperature and pressure, equal volumes of all gases contain:

The empirical formula of a compound is CH₂O and its molecular mass is 180 g/mol. What is its molecular formula?

Which law states that 'matter can neither be created nor destroyed in a chemical reaction'?

The energy of an electron in the nth orbit of hydrogen-like ion He⁺ is given by Eₙ = –(2.178 × 10⁻¹⁸ × Z²)/n² J. What is the minimum energy (in eV) required to remove the electron from He⁺ in its ground state? (1 eV = 1.6 × 10⁻¹⁹ J)

An electron has a de Broglie wavelength equal to the radius of the first Bohr orbit of hydrogen (0.529 Å). What is the velocity of this electron? (h = 6.626 × 10⁻³⁴ Js, mₑ = 9.108 × 10⁻³¹ kg)

Which of the following sets of quantum numbers is VALID for an electron in a 4f orbital?

Electron gain enthalpy of fluorine (–328 kJ/mol) is LESS negative than that of chlorine (–349 kJ/mol), contrary to the expected periodic trend. Which explanation is most accurate?

Using Mendeleev's predictions, ekasilicon was predicted to have an oxide formula of MO₂ and a chloride of MCl₄. When the element was discovered as Germanium (Z=32), these predictions were confirmed. What is the IUPAC systematic name for the element with atomic number 115, as per IUPAC nomenclature r

Which of the following correctly explains why the ionic radius of Mg²⁺ (0.65 Å) is smaller than that of Na⁺ (0.95 Å), given that both ions are isoelectronic with 10 electrons?