Bài 7: Nung m gam bột sắt trong oxi, thu được 3 gam hỗn hợp chất rắn X. Hòa tan hết hỗn hợp X trong dung dịch HNO3 (dư), thoat ra 1,68 lit (đktc) NO2

Bài 7: Nung m gam bột sắt trong oxi, thu được 3 gam hỗn hợp chất rắn X. Hòa tan hết hỗn hợp X trong dung dịch HNO3 (dư), thoat ra 1,68 lit (đktc) NO2 (là sản phẩm khử duy nhất). Gia trị của m là? Bài 8: Để m gam phoi bào sắt ngoài … Đọc tiếp

1.Choose the correct answer. 1. He was writing to his friend when he __________a noise. A. was hearing B. heard C. had heard D. hears 2. I _______

1.Choose the correct answer. 1. He was writing to his friend when he __________a noise. A. was hearing B. heard C. had heard D. hears 2. I __________many people since I came here in June. A. met B. has met C. was meeting D. have met 3. We __________ maths at this time last week. … Đọc tiếp