Why? The Best Ever Question and Answer Book about Nature, Science and the World Around You by Catherine Ripley, illustrated by Scot Ritchie

From chapters.ca:
Everyday childhood activities, such as an excursion to the park, splashing in the bathtub, or fixing a snack in the kitchen, can prompt many questions from young children. Why is the sky blue? Why does my stomach g-r-r-owl? Why do cows moo? Curious kids want to know, and no adult has all the answers. Since 2001, Why? has taken over 100,000 young readers inside the kitchen and out to the park, from the farm to the supermarket, and from bath time to bedtime.