Depends on how sensible the child is. I would be fine leaving DS1 alone in this situation, he is 11yo, in Y7. However, I highly doubt that I could do the same with 10yo DS2 when he is in Y7. You ne ed to make an informed decision based upon THAT child's capabilities.
DS1 was classed as Fraser competent in a Family Court at 9yo, though, has an IQ of 134, and is VERY sensible - without being asked, it occurs to him to text me if his bus home from school is running more than 10 minutes late. He can use a microwave and the oven to cook himself a snack, he knows my mobile number off by heart, and he can quickly respond to even emergency situations. (He has had to in the past due to my epilepsy).
DS2 is silly, jumps around and ends up hurting himself, can't make himself a sandwich at 10yo, and often answers the door despite being told not to when I'm IN the house. Goodness knows what he would do if he was on his own!
So it is really down to each individual child. If you feel uneasy about it, then chances are that you aren't SURE that your DC is 'ready' to be left alone. I had terrible misgivings about leaving my DD when she was 13, I had no such misgivings about leaving DS1 at 11.
In fact, due to appointments, the only time I can food shop this week is this morning. DS1 is off school with D&V. He will have the home phone and mobile in his bedroom, and will text me if he feels any worse. I can trust him to take the correct dose of medicine if he has a temperature, which he checks carefully with a thermometer first, and texts me for advice... It is down to the fact that DS1 was born with a cardigan and slippers that I feel safe trusting him at home alone.