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- Chemical Reactions & Equations
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- Carbon & Its Compounds
- Periodic Classification of Elements
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- How Do Organism Reproduce
- Heredity and Evolution
- Light: Reflection and Refraction
- Human Eye and Colorful World
- Electricity
- Magnetic Effect of Electric Current
- Sources of Energy
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- Management of Natural Resources
Popular Questions
- Name two elements whose valencies are equal to their group number.
- Assertion : Be, Mg and Ca can be classified Reason : Atomic mass of Mg is approximately
- Which of the following statements is not a correct statement
- X is an element with atomic number 20.
- Assertion : Sodium is an element of group 1 of the modern periodic table. Reason : All the elements of group 1 of the modern perio..
- identify and name the metals out of the following elements whose electronic configurations are given below.
- Name two elements you would expect to show chemical reactions similar to magnesium.
- Account for the following: Elements of group 18 are called zerovalent
- Write the atomic numbers of two elements X and Y having electronic configuration 2,8,2 and 2,8,6 respectively.
- Why does silicon has valency 4 and chlorine 1?
- Assertion : Atomic size increase on going down the group Reason : New shells are being added as we go
- What were the criteria used by Mendeleev in creating his periodic table?
- Out of two elements, potassium and sodium, which one can lose electron easily? Give reason for your answer
- An element Y has a total of three shells, with six electrons in its valence shell.
- X is an element of modern periodic table. It is surrounded by elements having atomic number 17, 34, 36 and 53.
- Hydrogen occupies a unique position in modern periodic table, justify the statement.
- Two elements A and B belong to the 3rd period of modern periodic table and are in group 2 and 13 respectively.
- Out of the two elements x and y which has bigger atomic radius?
- Four elements P, Q, R and S have atomic numbers 12, 13, 14 and 15 respectively.
- Did Dobereiners triads also exist in the columns of Newlands octaves? Compare and find out
- What type of oxide would Eka-aluminium form?
- Upto which element, the law of octaves was found to be applicable
- The possition of three elements X, Y and Z in the periodic table is given below.
- An element X belongs to group 2 and period 3 of the periodic table. The chemical formulae of its nitrate, sulphate and phosphate r..
- What were the limitations of Dobereiners classification?
- Which of the following element is not the member of second period?
- Give an account of the process adopted by Mendeleev for the clarification of elements. How did he arrive at "periodic law"?
- Atoms of seven elements A, B, C, D, E, F and G have different number of electronic shells but have the same number of electrons in..
- The element of a period of the periodic table are given below in order, from left to right with one of its element missing.
- (i) In this ladder (figure) symbols of elements are jumbled up. (ii) Arrange them in the order of their group also
- Which of the following elements belong to (i) same period? (ii) same group Explain giving reason.
- The electronic configuration of an element X is 2, 8, 8, 2.
- Name (i) Two elements having valency 2 (ii) Two elements forming oxides (iii) An element having numbers of electrons double
- Assertion : Elements of group 16 are monovalent. Reason : Elements of group 16 have seven electrons
- Name (i) three elements that have a single electron (ii) two elements that have two electrons (iii) three elements with filled ou..
- Assertion : Electronegativity of flourine is Reason : The electronegativity of the elements increases
- (i) How does electronic configuration of an atom (ii) which element has a total of three shells
- The element with atomic number 14 is hard and forms acidic oxide and a covalent halide.
- Write the correct increasing order of the atomic radii of O, F and N.
- (i) Lithium, sodium and potassium are all metals that react with water (ii) Helium is an unreactive gas and neon is a gas
