1 .c
2.B
3.C
4.C
5.B
6.D
Phan tu luan.
1. quang hop la qua trinh tong hop chat huu co tu cac chat vo co(CO2 , H2O) nho nang luong anh sang duoc hap thu boi he sac to thuc vat
_Y nghia : quang hop la mot qua trinh ma tat ca su song tren Trai Dat deu phu thuoc vao no
2. s
goi so co 6 chu so khac nhau la:abcdzt
-Tong co cac so co 6 chu so khac nhau la :9*9*8*7*6*5=136080(so)
-tong c cac so co 6 chu s khac nhau ma khong co mat chu s 1 va so 0 la :8*7*6*5*4*3 =20160 (so).
vay cacso co 6 chu so luon co mat chu so 1 va 0 la :136080-20160 =115920 .