The electronic configuration of the elements A and B are 1s², 2s ²,2p⁶,3s² and 1s², 2s²,2p⁵ respectively. The formula of the ionic compound that can be formed between these elements is ___________

Which of the following elements will have the highest electro negativity ____________

Various successive ionisation enthalpies (in kJ mol^-1) of an element are given below.

The element is

The correct order of decreasing electronegativity values among the elements X, Y, Z and A with atomic numbers 4, 8,7 and 12 respectively

How does electron affinity change when we move from left to right in a period in the periodic table?

______ is the lightest metal known.

Which of the following set has atomic numbers of only representative elements?

The element with atomic number 103 is ______

Match the list I with list II and select the correct answer using the code given below the list.

Consider the following statements
(i) In Chancourtois classification, elements differed from each other in atomic weight by 16 or multiples of 16 fell very nearly on the same vertical line.
(ii) Mendeleev's periodic law is based on atomic weight.
(iii) Mendeleev listed the 117 elements known at that time and are arranged in the order of atomic numbers.
Which of the following statement is/are not correct?

For decolorisation of 1 mole of acidified KMnO₄, the moles of H₂O₂ required is ___________

Volume strength of 1.5 N H₂O₂ is _____________

The hybridisation of oxygen atom is H₂O and H₂O₂ are, respectively __________

Hydrogen burns in air with a - flame.

The element which does not contain a neutron is _____________

Hydrogen combines with carbon monoxide in the presence of copper catalyst will synthesise _____________

Liquid hydrogen is used as ___________

Which one of the following is used as water softener?

Statement-I: The magnetic moment of parahydrogen is zero.
Statement-II: The spins of two hydrogen atoms in para H2 molecule neutralise each other.

Statement-I: Heavy water has been widely used as moderator in nuclear reactors.
Statement-II: Heavy water can lower the energies of fast moving neutrons.

Define modern periodic law.

Define electro negativity.

How would you explain the fact that the second ionisation potential is always higher than first ionisation potential?

How does atomic and ionic radii vary across the group and period.

Mention the characteristics of 's' block elements.

Mention the characteristics of 'd' block elements.

How does ionisation energy vary in a group?

How is ionisation energy related to the metallic character? How does the basic nature of hydroxides of alkaline earth metals very down the group?

Predict the position of the element in periodic table satisfying the electronic configuration (n-1)d², ns² where n =5

The electron gain enthalpy of chlorine is 348 kJ mol^-1. How much energy in kJ is released when 17.5 g of chlorine is completely converted into Cl^- ions in the gaseous state?

Explain why hydrogen is not placed with the halogen in the periodic table.

An the cube at 0°C is placed in some liquid water at 0⁰C, the ice cube sinks - Why? An ice cube at 0°C is placed in some liquid water at 0°C, the ice cube sinks. What is the nature of water? Justify.

Predict which of the following hydrides is a gas on a solid
(a) BCI
(b) NaH 
Give your reason.

Write chemical equation for the following reactions.
i) reaction of hydrogen with tungsten (VI) oxide on heating.
(ii) hydrogen gas and chlorine gas.

Why interstitial hydrides have a lower density than the parent metal.

Explain the large scale production of Hydrogen.

Life underneath frozen lakes survive even bitter winter. Justify.

Give the reaction which takes place in H₂ - O₂ fuel cells.

What is the nuclear reaction that take place in the sun and other stars?

Write a note about gas hydrates.

Energy of an electron in the ground state of the hydrogen atom is -2.8 x 10^-18 J. Calculate the ionisation enthalpy of atomic hydrogen in terms of kJ mol^-1.

The electronic configuration of atom is one of the important factor which affects the value of ionisation potential and electron gain enthalpy. Explain.

In what period and group will an element with Z = 118 will be present?

Justify that the fifth period of the periodic table should have 18 elements on the basis of quantum numbers.

Elements a, b, c and d have the following electronic configurations:
a: 1s², 2s², 2p⁶
b: 1s², 2s², 2p⁶, 3s², 3p¹
c: 1s², 2s², 2p⁶, 3s², 3p⁶
d: 1s², 2s², 2p¹
Which elements among these will belong to the same group of periodic table.

Write the name and deduce the atomic number of the following element
i. The second alkali metal
ii. The fourth noble gas
iii. The third halogen
iv. The first transition element

Which among the halogens would you expect to have the least electronegativity and why?

Which of the following pairs of elements would you expect to have higher ionisation energy?
(i) CI or F
(ii) S or C
(iii) Na or Ne
(iv) Ar or Kr.

How many elements are there in 6^th period? Prove it.

Prove that valency is a periodic property.

Complete the following chemical reactions and classify them into
(a) hydrolysis (b) redox (c) hydration reactions.
(1) KMnO₄ + H₂O₂ ➝
(2) CrCl₃ + H₂O ➝
(3) CaO + H₂O ➝

Explain the exchange reactions of deuterium.

How do you convert para hydrogen into ortho hydrogen?

Mention the uses of deuterium.

Why is water molecule polar?

Do you think that heavy water can be used for drinking purposes?

Name "two hydrides which are used as reducing agents in organic chemistry. How are they prepared?

Give a brief account of ionic hydrides.

Compare the properties of isotopes of hydrogen.

What are metallic hydrides? Explain about it.

Explain the pauling method for the determination of ionic radius.

Explain the diagonal relationship.

Why the first ionisation enthalpy of sodium is lower than that of magnesium while its second ionisation enthalpy is higher than that of magnesium.

What is screening effect? Briefly give the basis for pauling's scale of electronegativity.

State the trends in the variation of electronegativity in group and periods.

Give the structural features of modern periodic law.

Give the characteristics of p-block elements.

Calculate the ionic Radii of Na⁺ and F^- ion in NaF crystal whose interionic distance is equal to 231 pm

(a) State Mendeleev's periodic law.
(b) Describe about the merits of Mendeleev's periodic table.

Explain about the structural features of Moseley's long form of periodic table.

An isotope of hydrogen (A) reacts with diatomic molecule of element which occupies group number 16 and period number 2 to give compound (B) is used as a moderator in nuclear reaction. (A) adds on to a compound ( C), which has the molecular formula C₃H₆ to give (D). Identify A, B, C and D.

Compare the structures of H₂O and H₂O₂ .

How does heavy water react with the following compounds ?
(i) Al₄C₃
(ii) CaC₂
(ill) Mg₃N₂ and
(iv) Ca₃P₂

(i) How does the hard water affect the boilers?
(ii) Soap forms lather with soft water but does not form lather with hard water. Why?

Explain the following methods involved in removing the permanent hardness.
(a) Treatment with sodium carbonate
(b) Ion-exchange method

Identify the nature of hydrides that are formed by the elements of atomic numbers 15, 19, 23, 44 with dihydrogen. Compare their reactivity towards water.

An element (A) belonging to group number 1 and period number 3 react with dihydrogen to form anhydride (B). The element (A) reacts with the universal solvent to give a strong base (C). Identify A, B, and C.

Dihydrogen reacts with dioxygen (O₂) to form water. Write the name and formula of the product when the isotope of hydrogen which has one proton and one neutron in its nucleus is treated with oxygen. Will the reactivity of both the isotopes be the same towards oxygen? Justify your answer.

When the first element of the periodic table is treated with dioxygen, it gives a compound whose solid state floats on its liquid state. This compound has an ability to act as an acid as well as a base. What products will be formed when this compound undergoes autoionisation ?

How are reducing agents in synthetic organic chemistry prepared?