Which contract is void ab initio?

While entering into contract to see a cow, a disclosed B that the cow gives five liters milk in a day whereas it gives four liters in a day

At the time of contract of selling a car, A told B that mileage of the car is 20 km per litre whereas its mileage is 18 km per litre

At the time of contract, A told B that the area of his house is 1400 sq. feet but on measurement the area of the house is found 1398 sq. feet