(1)铁粉和硫黄在两块玻璃片之间,反应时几乎接触不到氧气,减少了
(2)向反应后的黑色固体滴入稀硫酸,有臭鸡蛋气味的硫化氢气体产生,说明铁粉和硫黄发生反应。中硫元素的化合价为
(3)反应后的黑色固体加入,溶液中,生成红色物质,说明黑色固体中有
同类型试题
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2