A.可以用稀盐酸清洗用过的铂丝或光洁无锈的铁丝 |
B.焰色试验是元素的化学性质 |
C.焰色试验时应将玻璃棒洗净后先在外焰上灼烧至与原来的火焰颜色相同,再蘸取待测物实验 |
D.焰色通过蓝色的钴玻璃没有观察到黄色,则一定不含钠元素 |
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