Questions

Two series alternate here, with every third number following a different pattern.
In the main series, 4 is added to each number to arrive the next.
In alternate series, 5 is subtracted from each number t arrive the next number.
Here in the main series 
3 + 4 = 7
7 + 4 = 11
11 + 4 = 15
15 + 4 = 19

In alternate series 
24 - 5 = 19
19 - 5 = 14...

Lactose is the major carbohydrate in the milk of most species.

Lactose is a disaccharide composed of the monosaccharides D-glucose and D-galactose, joined in a ß-1,4-glycosidic linkage. The chemical name for lactose is 4-0-ß-D-galactopyranosyl-D-glucopyranose.

Water containing caustic soda cannot be used for drinking

A Kitten.

Beautiful means good looking, having pleasing personality, glamourous, charming.

Synonyms of Beautiful are handsome, attractive, alluring, cute, fair,...

Hence, in the given options Synonym of 'Beautiful' is Alluring.

IEEE 1284 is a standard that govern parallel communications.

• IEEE 1284 is a standard that defines bi-directional parallel communications between computers and other devices.

• It was originally developed in the 1970s by Centronics, and was widely known as the Centronics port, both before and after its IEEE standardization.