There are three main groups of oils-animal, vegetable and mineral. Great quantities of animal oil come from whales, creatures of the sea, which are the largest of the animals remaining in the world. To protect the whales from the cold of the Artic seas, nature has provided them with a thick covering of fat, called blubber. When the whale is killed, the blubber is stripped off and boiled down. It produces a great quantity of oil which can be made into food for human consumption. A few other creatures yield oil, but none so much as the whale. The livers of the cod and halibut, two kinds of fish, yield nourishing oil. Both cod liver oil and halibut oil are given to sick children and other invalids who need certain vitamins.. 
Vegetable oil has been known from very old times. No household can get on without it, for it is used in cooking. Perfumes may be made from the oils of certain flowers. Soaps are made from eatable and animal products and the oils of certain flowers. 

The main source of animal oil, is –

12 लीटर वाले नमक मिश्रण में 7 प्रतिशत नमक है । यदि उसे गर्म किया जाता है तो 4 लीटर पानी वाष्प बन जाता है, तो बचे हुए मिश्रण में नमक कि मात्रा हैं? 

झूठ का पता लगाने वाला यंत्र किस नाम से जाना जाता है? 

यदि a + b + c = 12, a² + b² + c² = 52, हो, तो ab + bc + ca बराबर है?

ग्लोबल फायरपावर इंडेक्स, 2021 में चौथा स्थान निम्न में से किस देश को प्राप्त हुआ है ?