Scheda di esercizi di Chimica per i test di ammissione a infermieristica con soluzioni

About what percentage of dry air is oxygen?

1. A21%
2. B50%
3. C1%
4. D78%

How many moles of oxygen atoms are in 1 mole of carbon dioxide, CO₂?

1. A1
2. B0,5
3. C3
4. D2

What is activation energy?

1. AThe energy needed to melt a solid
2. BThe minimum energy reacting particles need for a reaction to happen
3. CThe total energy released once the reaction has finished
4. DThe energy stored in the products

Come influisce di solito l'aumento di temperatura sulla velocità di una reazione?

1. AFerma completamente la reazione
2. BDiminuisce la velocità
3. CAumenta la velocità
4. DNon ha effetto sulla velocità

How does a mixture of iron filings and sulfur powder differ from the compound iron sulfide?

1. AThe compound keeps the magnetic properties of iron
2. BThe mixture can be separated physically, for example with a magnet
3. CThe mixture is formed by a chemical reaction between the two elements
4. DThe mixture has a fixed ratio of iron to sulfur

Why must temperatures be in kelvin in gas law calculations?

1. AGas volume and pressure are proportional to the absolute temperature
2. BThe kelvin scale has smaller degrees, which gives more precise answers
3. CKelvin values are always below 100
4. DCelsius can only be used for liquids

Si mescolano volumi uguali di HCl 1 M e NaOH 1 M. Qual è il pH approssimativo del risultato?

1. A3,5
2. B7
3. C1
4. D14

A compound has the empirical formula CH₂ and a molar mass of 42 g/mol (C = 12, H = 1). What is its molecular formula?

1. AC₂H₄
2. BC₄H₈
3. CCH₂
4. DC₃H₆