A.用洁净的铂丝蘸取NaCl和KCl的混合液,在酒精灯火焰上灼烧,火焰呈黄色 | B.向充满干燥的集气瓶中放入有色鲜花,一段时间后,鲜花颜色变浅 | C.向过氧化钠粉末中加入少量水,产生的气体可以使带火星的木条复燃 | D.将钠投入硫酸铜溶液中,钠浮在液面上,烧杯底部产生红色固体 |
A.A | B.B | C.C | D.D |
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