Google is an inappropriate searcher. There is so many bad and insecure pictures! If found a pic that had so many bad words! And really it's iffy for my age. When it comes to Google you have to watch out.
If you trust that your chilsd will not google innapropriat things then by all means allow them to use google. If not, then no! This has nothing to do with your childs age, it has to do with how much that you trust your child. If you say to a 7 year old, "When you're 12 you can go on Google." That makes no sense because there are many 7 year olds that can handle the responsibility of Google, and many 12 year olds that can't. So, just ask yourself, do you trust your kid.
Google is the biggest search engine and anyone can use it. No concerns, no ads, no bad language, no drugs, no violence. The highlight is that it's great for work and school.
Google scholar is one of the best sites to use when it comes to research. The advanced search is great, it really narrows things down, but the site isnt for everday research, its more for articles and papers that you may find in libraries. Its one of the best sites Ive been on for a long time.
I think that it doesn't really mater about the age it maters about how much you trust your kids. Google doesn't block any language, or inappropritate user content, or sexual behavior.
My parents says "don't say bad words or search bad things or anything else bad,mad,sad or rocketory or mean or unnice if you're a kid or a young/mature teen! it's not good for you!"