'What are black holes?', 'how did the world begin?' and 'how does the internet work?' are among questions asked by kids parents struggle to answer, a study has found.
A poll of 2,000 mums and dads found 54 per cent are regularly flummoxed by the deep and meaningful or scientific questions put to them by their children.
In fact, the average mum and dad face eight questions a month from their offspring which they find difficult to respond to, either because they don't know the answer or are too embarrassed.
And 53 per cent admit that the more scientific the question, the less likely they are to be able to answer it.
Other questions parents struggle to answer include 'why do people die?', 'why is the sea salty?' and 'how does the internet work?'
It also emerged the average parent will turn to Google six times a month to get the answer to a question their child has asked.
A spokesman for ACS, which commissioned the research to mark the opening of the new Science Centre at its Hillingdon school, said: "Children are known for always asking questions, but it can be difficult when they want to know things parents themselves don't know the answer to.
"Sometimes mums and dads will stumble with their reply as it's an awkward question or they know the answer is going to lead to more potentially embarrassing questions.
"But inquisitive children are also asking lots of questions about the planet, how things work and science which are leaving parents struggling to give them the right answer.
"It's important to encourage your children's thirst for learning new things and even if you have to Google the answer yourself, it can help them develop an interest in an important subject as they get older."
The study, carried out through OnePoll, found 'what does God look like?' is the question most likely to leave parents stumped, followed by what came first, the chicken or the egg?' and where do you go when you die?'.
'What are black holes?' came fifth with 'why is water wet?', 'why do people die?' and 'how did the world begin?' close behind.
'Where do babies come from?', 'why is the sea salty?' and 'why is the moon sometimes out in the day?' completed the top ten.
Other questions from intrigued youngsters which leave parents scratching their heads include 'why is the sky blue?', 'what makes the earth spin?' and 'how do planes fly?'.
But while 47 per cent of parents just respond with an honest 'I don't know', 28 per cent admit to trying to cobble together an answer which sounds like it could be right while 35 per cent tell the youngster to Google it.
Twenty-three per cent Google it themselves and then pretend they knew the answer all along while others tell the child to ask their teacher (14%) or a sibling or other parent (11%).
Thirty-three per cent of parents even admitted to knowingly telling their children the wrong answer because they didn't want to admit they didn't know.
But 80 per cent of parents admit this has back fired when their children have then repeated the wrong answer to other people because they believed it to be right.
A spokesman for ACS added: "The extent to which science based subjects grab children's interests is fascinating. It certainly underpins our commitment to equipping our teachers and students with the very facilities and skills they need to teach, learn and develop this obvious early curiosity.
"It's clear too that parents should be brought into the picture too as they are quite clearly struggling to cope with many of the questions posed by their inquisitive offspring."
Top 30 impossible questions
1. What does God look like?
2. What came first, the chicken or the egg?
3. Where do you go when you die?
4. What are black holes?
5. Why is water wet?
6. Why do people die?
7. How did the world begin?
8. Where do babies come from?
9. Why is the sea salty?
10. Why is the moon sometimes out in the day?
11. How does the internet work?
12. Why is the sky blue?
13. Where does wind come from?
14. Why do we have a leap year?
15. What makes the Earth spin?
16. Why is blood red?
17. What is infinity?
18. How big is the world?
19. Why doesn't the sky fall down?
20. Why does cutting onions make you cry?
21. How do planes fly?
22. How do telephones work?
23. How does TV work?
24. Why am I right/left handed?
25. What is electricity?
26. How do clouds float?
27. How does the car work?
28. How do the sun and moon stay in the sky?
29. Why are people's eyes different colours?
30. How does lightning strike?