Which element has
(a) two shells, both of which are completely filled with electrons?
(b) the electronic configuration 2, 8, 2?
(c) a total of three shells, with four electrons in its valence shell?
(d) a total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?
(a) Neon has two shells, both of which are completely filled with electrons (K shell with 2 electrons and L shell with 8 electrons).
(b) Magnesium has the electronic configuration 2, 8, 2.
(c) Silicon has a total of three shells, with four electrons in its valence shell (K shell with 2 electrons, L shell with 8 electrons and M shell with 4 electrons.)
(d) Boron has a total of two shells, with three electrons in its valence shell (K shell with 2 electrons and L shell with 3 electrons).
(e) Carbon has twice as many electrons in its second shell as in its first shell (K shell with 2 electrons and L shell with 4 electrons).
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
The position of three elements A, B and C in the Periodic Table are shown below –
Group 16 Group 17
- -
- A
- -
B C
(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?
Compare and contrast the arrangement of elements in Mendeléev’s Periodic Table and the Modern Periodic Table.
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
How could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table?
Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as
(a) Na (b) Mg (c) AI (d) Si
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
In the Modern Periodic Table, which are the metals among the first ten elements?
Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, AI, Si, Ba.
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
What are the differences between the transport of materials in xylem and phloem?
How does the creation of variations in a species promote survival?
What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.
A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.
Name some devices in which electric motors are used.
Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?
You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
What are oxidising agents?
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as
(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw
Differentiate between metal and non-metal on the basis of their chemical properties.
Class X 1st unit test answer