List of practice Questions

How does atomic radius vary in a period and in a group? How do you explain the variation?
What does atomic radius and ionic radius really mean to you?
Why do elements in the same group have similar physical and chemical properties?
Which element do you think would have been named by
(i) Lawrence Berkeley Laboratory
(ii) Seaborg's group?
Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
In terms of period and group where would you locate the element with Z =114?
If all the waste we generate is biodegradable, will this have no impact on the environment?
On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
What is the basic difference in approach between the Mendeleev's Periodic Law and the Modern Periodic Law?
Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that? 
What are the problems caused by the non biodegradable wastes that we generate?

The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.

Literacy rate (in %)45 - 5555 - 6565 - 75 75 - 85 85 - 95
Number of cities

11

10

7

4

4

What is the basic theme of organisation in the periodic table?

A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.

Number of Days0 - 6 6 - 1010 - 1414 - 2020 - 2828 - 3838 - 40
Number of Students111074431

To find out the concentration of SO\(_2\) in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:

Concentration of SO\(\bf{_2}\) (in ppm)Frequency

0.00 - 0.04 

0.04 - 0.08 

0.08 - 0.12 

0.12 - 0.16 

0.16 - 0.20 

0.20 - 0.24 

4

9

9

2

4

2

A cross was made by Mendel with pea plant between violet flower (VV) in axial position (AA) and while flower (vv) in terminal position (aa). What ratio of white flowers (vv) phenotypically he had received in F2 generation?

Thirty women were examined in a hospital by a doctor and the number of heartbeats per minute were recorded and summarised as follows. Find the mean heartbeats per minute for these women, choosing a suitable method.

Number of heartbeats per minute65 - 6868 - 7171 - 7474 - 7777 - 8080 - 8383 - 86
Number of boxs2438742

The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs 18. Find the missing frequency f.

Daily pocket11 - 1313 - 1515 - 1717 - 1919 - 2121 - 2323 - 25
Number of workers76913f54

A survey was conducted by a group of students as a part of their environment awareness programme, in which they collected the following data regarding the number of plants in 20 houses in a locality. Find the mean number of plants per house. 

Number of plants  0 − 22 − 4 4 − 66 − 8 8 − 1010 − 1212 − 14
Number of houses

1

2

1

5

6

2

3

Which method did you use for finding the mean, and why?

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
The graphs shows, angular velocity as a function of time. In which one is the magnitude of the angular acceleration constantly decreasing?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
Explain why the planets do not twinkle?