Lovely Lemons in Discovery Time

In discovery time we washed the windows in Room 9 after Mrs Keane drew on them with oil and crayons and bits of blue tack. First we used just water then we tried lemon juice. That worked really well, especially to get the blue tack off. We wondered if this is why lots of cleaning products have lemon in them? The lemon also smells so nice so maybe that is why they put it in cleaning products as well.
How could we find out?