ใบงาน เคมีสำหรับข้อสอบเข้าพยาบาล พร้อมเฉลย

ข้อใดต่อไปนี้เป็นการเปลี่ยนแปลงทางเคมี

1. Aน้ำตาลละลายในชา
2. Bน้ำแข็งละลาย
3. Cไม้ไหม้
4. Dแก้วแตก

What is the formula of sulfuric acid?

1. AHNO₃
2. BH₂SO₄
3. CH₂SO₃
4. DHCl

What are the usual units of molar mass?

1. Amol/L
2. Bg/L
3. Cmol/g
4. Dg/mol

When diluting a concentrated acid, which method is safe?

1. AAdd the water slowly to the acid
2. BAdd the water quickly to the acid
3. CMix them in any order, as long as it is fast
4. DAdd the acid slowly to the water

Which coefficients balance __KClO₃ → __KCl + __O₂?

1. A1, 1, 1
2. B2, 2, 3
3. C2, 1, 3
4. D1, 1, 3

A plastic block has a density of 0.8 g/cm³. What happens when it is placed in water (density 1.0 g/cm³)?

1. AIt dissolves
2. BIt floats
3. CIt stays suspended halfway down
4. DIt sinks

What is the oxidation number of manganese in potassium permanganate, KMnO₄?

1. A+4
2. B+7
3. C−1
4. D+1

Raising the temperature by 10 °C can roughly double the rate of many reactions. What is the main reason?

1. AThe reaction becomes more exothermic
2. BThe activation energy itself is lowered by the extra heat
3. CMany more collisions have at least the activation energy
4. DThe particles become larger and easier to hit