19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
In the fourth period of the periodic table, how many elements have one or more 4d electrons?
Elements whose outer electronic configuration vary from ns2np1 to ns2np6 constitute
The periods in the Periodic Table are numbered from
Lothar Meyer plotted the physical properties such as atomic volume, melting point and ….A…..against atomic weight. Here, A refers to
According to Alexander Newlands, elements are arranged in…..A….order of their atomic weights. Here A refers to
John Alexander Newlands relationship referred to as the …….A…… Here, A refers to
Which of the following is not a Dobereiner’s triad?
The correct order of decreasing electronegativity values among the elements I-beryllium, II-oxygen, III-nitrogen and IV-magnesium, is (Kerala CEE 2011)
Assertion: Boron has a smaller first ionization enthalpy than beryllium. Reason: The penetration of a 2s electron to the nucleus is more than the 2p electron hence 2p electron is more shielded by the inner core of ele…
Assertion: Generally, ionization enthalpy increases from left to right in a period. Reason: When successive electrons are added to the orbitals in the same principal quantum level, the shielding effect of the inner co…
Assertion: Third ionization energy of sulphur is larger than phosphorous. Reason: There is a larger amount of stability associated with filled s- and p- sub-shells (a noble gas electron configuration) which correspond…
Which of the following properties shows a gradual decrease with an increase in atomic number across a period in the periodic table?
Consider the following statements: (I) The radius of an anion is larger than that of the parent atom. (II) The ionization energy generally increases with the increasing atomic number in a period. (III) The electronega…
From which of the following species it is easiest to remove one electron?
For a given value of n (principal quantum number), ionization energy is highest for
IE1 and IE2 of Mg(g) are 178 and 348 kcal mol–1 respectively. The energy required for the reaction Mg (g) ® Mg2+ (g) + 2e– is
Which of the following isoelectronic ions has the lowest ionization energy?
The order of screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on its outer shell electrons is:-
Consider the isoelectronic species, Na+, Mg2+,F –and O2–. The correct order of increasing length of their radii is ...........
For the second period elements the correct increasing order of first ionization enthalpy is (NEET 2019)
Which of the following oxides is most acidic in nature ? (NEET 2018)
The formation of the oxide ion, g O from oxygen atom requires first an exothermic and then an endothermic step as shown below: (NEET 2015) o f g g O e O ; H 141kJmol -> o f g g O e O ; H 780kJmol -> …
Which of the following orders of ionic radii is correctly represented? [AIPMT 2014]
Amongst the following, select the element having highest ionisation enthalpy. (MHT CET 2014)
The compound not acting as a reducing agent is (Manipal 2014)