... ca X l: Cõu 20: Khi tng s electron ca 4s v 3d l 11. Thỡ nguyờn t ú cú v trớ nh th no trong bng HTTH. Cõu 21: Cho 2 nguyờn t M v N cú Z ln lt l 11 v 13. Vit cụng thc oxit, hiroxit m M v N to ra. ... ca X l: Cõu 20: Khi tng s electron ca 4s v 3d l 11. Thỡ nguyờn t ú cú v trớ nh th no trong bng HTTH. Cõu 21: Cho 2 nguyờn t M v N cú Z ln lt l 11 v 13. Vit cụng thc oxit, hiroxit m M v N to ra. ... 19p v 19e. Cõu 5: Bit rng khi lngmt nguyờn t oxi nng gp 15,842 ln v khi lng ca nguyờn t C nng gp 11, 9059 ln khi lng ca nguyờn t H. Nu chn 1/12 khi lng nguyờn t C lm n v thỡ O, H cú nguyờn t khi...