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?
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?
Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, AI, Si, Ba.
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?
How are the alveoli designed to maximise the exchange of gases?
The xylem in plants are responsible for
(a) transport of water. (c) transport of amino acids.
(b) transport of food. (d) transport of oxygen.
Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
Name the sodium compound which is used for softening hard water.
What change will you observe if you test soap with litmus paper (red and blue)?
If all the waste we generate is biodegradable, will this have no impact on the environment?
The phenomenon of electromagnetic induction is
(a) the process of charging a body.
(b) the process of generating magnetic field due to a current passing through a coil.
(c) producing induced current in a coil due to relative motion between a magnet and the coil.
(d) the process of rotating a coil of an electric motor.
Why are some substances biodegradable and some non-biodegradable?
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm.
(b) A concave lens of focal length 50 cm.
(c) A convex lens of focal length 5 cm.
(d) A concave lens of focal length 5 cm.
Class X 1st unit test answer