Short Answer TypeThe elements Be, Mg and Ca each having two electrons in their outermost shells are in periods 2, 3, and 4 respectively of the modern periodic table. Answer the following questions, giving justification in each case:
(i) Write the group to which these elements belong.
(ii) Name the least reactive element.
(iii) Name the element having a largest atomic radius.
A carboxylic acid (molecular formula C2H402) reacts with an alcohol in the presence of an acid catalyst to form a compound 'X'. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid C2H402. Write the name and structure of
(i) carboxylic acid, (ii) alcohol and (iii) the compound 'X'.
Define the term ‘structural’ isomerism'. Explain why propane cannot exhibit this property. Draw the structures of possible isomers of butane, C4H10 .
Structural isomerism can be defined as a carbon compound which has same molecular formula but different structural formula.
Propane has the chemical formula C3H8 and it is represented as CH3-CH2-CH3. In alkanes, isomerism arises when a particular compound can be represented in the form of both straight chain and branched chain. Also, the branching cannot be done from the first or the last carbon atom of the structure.
The structural formulae of propane show that they do not have a sufficient number of carbon atoms to exist in the form of branched isomer. Hence, they do not exhibit structural isomerism.
Isomers of Butane: There are two isomers. N-butane and iso-butane.
A student wants to project the image of a candle flame on a screen 90 cm in front of a mirror by keeping the flame at a distance of 15 cm from its pole.
(a) Suggest the type of mirror he should use.
(b) Determine the linear magnification in this case.
(c) Find the distance between the object and its image.
(d) Draw ray diagram to show the image formation in this case.
Draw a ray diagram to show the path of the refracted ray in each of the following cases:
A ray of light incident on a concave lens is:
(i) passing through its optical centre.
(ii) parallel to its principal axis.
(iii) directed towards its principal focus.
A narrow beam PQ of white light is passing through a glass prism ABC as shown in the diagram.
Trace it on your answer sheet and show the path of the emergent beam as observed on the screen DE.
(i) Write the name and cause of the phenomenon observed.
(ii) Where else in nature is this phenomenon observed.
(iii) Based on this observation, state the conclusion which can be drawn about the constituents of white light.
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