Question

3 numeric 1 point how many protons does cu²+ have? answer 4 multiple choice 1 point which of these is an element? salt water oil and water oxygen salt 5 formula 1 point a gas occupies 409.3 ml at a temperature of 19.9°c. what is the volume, in ml, at 99.2°c? round to 1 decimal place.

Explanation:

Question 3

Step1: Recall atomic number of Cu

The atomic number of copper (Cu) is \(29\). The number of protons in an atom is equal to its atomic number.

Step2: Consider ion formation

When \(Cu^{2 + }\) is formed, electrons are lost. But the number of protons remains unchanged.

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Salt water is a mixture of salt (a compound) and water (a compound). Oil and water is a mixture of two different substances. Salt (\(NaCl\)) is a compound. Oxygen (\(O_2\)) is an element as it is made up of only one type of atom (\(O\) atoms).

Step1: Convert temperatures to Kelvin

Use the formula \(T = t+273.15\).
For \(t_1 = 19.9^{\circ}C\), \(T_1=19.9 + 273.15=293.05\space K\)
For \(t_2 = 99.2^{\circ}C\), \(T_2=99.2+273.15 = 372.35\space K\)

Step2: Apply Charles's Law

Charles's Law is \(\frac{V_1}{T_1}=\frac{V_2}{T_2}\), where \(V_1 = 409.3\space mL\), \(T_1 = 293.05\space K\), \(T_2=372.35\space K\).
We can solve for \(V_2\): \(V_2=\frac{V_1T_2}{T_1}\)
Substitute the values: \(V_2=\frac{409.3\times372.35}{293.05}\)

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Answer:

\(29\)

Question 4