ใบงาน เคมีสำหรับข้อสอบเข้าพยาบาล พร้อมเฉลย

What is a single covalent bond?

1. AThe attraction between two oppositely charged ions
2. BTwo pairs of electrons shared between two atoms
3. COne electron transferred from one atom to another
4. DOne pair of electrons shared between two atoms

What does the law of conservation of mass state?

1. AMass is neither created nor destroyed in a chemical reaction
2. BMass is lost as heat in every reaction
3. CGases have no mass
4. DThe mass of products is always greater than the mass of reactants

What kind of carbon–carbon bonds do alkanes contain?

1. AOnly single bonds
2. BAt least one double bond
3. CAt least one triple bond
4. DIonic bonds

A radioactive isotope has a half-life of 5 days. A sample starts with 80 g. How much is left after 10 days?

1. A20 g
2. B0 g
3. C10 g
4. D40 g

อะตอมของคลอรีน-37 มีโปรตอน 17 ตัว มีนิวตรอนกี่ตัว

1. A54
2. B20
3. C37
4. D17

Which property stays the same whether you have a small sample or a large sample of a pure substance?

1. AMass
2. BTotal heat content
3. CDensity
4. DVolume

CO₂ in blood forms carbonic acid: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. An anxious patient hyperventilates and breathes off extra CO₂. What happens to blood pH?

1. AIt stays exactly 7.40, because CO₂ does not affect pH
2. BIt falls, because oxygen is an acid
3. CIt rises, because less CO₂ means fewer H⁺ ions
4. DIt falls, because less CO₂ means more H⁺ ions

Pepsin digests protein in the stomach at about pH 2, but it stops working once food moves into the small intestine, where the pH is higher. Why?

1. AThe change in pH alters the shape of pepsin's active site
2. BPepsin only works on fats in the small intestine
3. CPepsin is used up completely in the stomach, just like a reactant
4. DThe small intestine is too cold for any enzyme