What are glycosidic linkages? In which type of biomolecules are they present?

Sucrose is dextrorotatory but after hydrolysis the mixture shows laevorotation,this is because of

Which among the following compounds is obtained when glucose reacts with hydrogen cyanide?

In fructose,the possible optical isomers are

Identify the carbon atoms of $\alpha$-glucose and $\beta$-fructose forming the glycosidic linkage in sucrose.

For 'invert sugar',the correct statement$(s)$ is(are)
(Given: specific rotations of $(+)$-sucrose,$(+)$-maltose,$L-(-)$-glucose and $(+)$-fructose in aqueous solution are $+66^{\circ}, +140^{\circ}, -52^{\circ}$ and $+92^{\circ}$,respectively)
$(A)$ 'invert sugar' is prepared by acid catalyzed hydrolysis of maltose
$(B)$ 'invert sugar' is an equimolar mixture of $D-(+)$-glucose and $D-(-)$-fructose
$(C)$ specific rotation of 'invert sugar' is $-20^{\circ}$
$(D)$ on reaction with $Br_2$ water,'invert sugar' forms saccharic acid as one of the products