Match the descriptions below with the graphs. Be sure to explain your answers.

Which of the following are SI units? Select<br> all that apply.

Dimas [21]

<h3>Answer:</h3>

Seconds (s)

Liters (L)

<h3>Explanation:</h3>

SI units relate to the International System of Units. These units are the base, metric units that are most commonly accepted for different measurements.

Common SI Units

The most common SI units are as follows:

Length - meter (m)
Time - second (s)
Mass - kilogram (kg)
Amount of substance - mole (mole)
Electric current - ampere (A)
Temperature - kelvin (K)
Volume - liter (L)

*Note that gram (g) is not an SI unit

Each type of measurement will only have 1 SI unit. This is the unit that will be expected for most answers. Sometimes this means converting an answer into a different unit so it is more widely accepted.

Why SI Units are Important

SI units are important for the same reason that the metric system is used. It gives a standardized list of measurements that scientists across the world can use. Also, it makes it easier to compare scientific findings and studies when all of the measurements are given in the same units.

There are times when it is unrealistic to use SI units. For example, when discussing space, using meters will not be realistic due to the size of space. Also, when measuring the mass of small elements, kilograms are too large. But otherwise, SI units should be used.

3 0

1 year ago

in Analytical chemistry laboratory. Nickle(ppm)in water sample estimated by two different students was as ,student 1 (25 24 24 2

frosja888 [35]

Answer:

Answers are in the explanation

Explanation:

Precision and accuracy are both statistical concepts. Precision is about how close are the measured values to each other. Accuracy is closeness of the measured values to a specific value or reference value.

There are many ways to calculate precision and accuracy, one is stimating precision as <em>Relative Uncertainty </em>and accuracy as <em>Relative Error.</em>

Formulas are:

Relative Uncertainty: Standard desviation / Measured value.

Relative Error: Measured Value - Expected Value / Expected value

<em>Measured value is the aveage of the values.</em>

<em />

For student 1:

Mean = 25

Standard desviation = 1.5275

Relative Uncertainty: 1.5275 / 25

Relative Uncertainty: 0.061

Relative Error: 25 - 20 / 20

Relative Error: 0.25

For student 2:

Mean = 24.5

Standard desviation = 0.5477

Relative Uncertainty: 0.5477 / 24.5

Relative Uncertainty: 0.02

Relative Error: 24.5 - 20 / 20

Relative Error: 0.225

<em>As the student 2 has a low Relative error and uncertainty, you can say student 2 is more accurate and precise</em>

6 0

3 years ago

Ascorbic acid (vitamin

svlad2 [7]

Let us see the structure of ascorbic acid

As shown there is no COOH group however the OH group can lose a proton and forms conjugate base

The conjugate base formed is stabilized due to resonance

More the stability of conjugate base more the strength of acid

Hence ascorbic acid behaves as an acid

8 0

3 years ago

Now select a longer period, say the fourth period, starting with the element in the 1A group. Again, go from left to right. What

Inessa [10]

Answer:

The pattern of change in the electron configuration increases from left to right across the period.

Explanation:

In the periodic table, elements having the same number of electrons in the outermost shell of their atoms are placed over one another in vertical columns. Each of the vertical columns is known as a group or family. while each of the resulting horizontal rows is known as a period or row.

There are 18 vertical columns and seven periods in the periodic table. Each period begins with an atom having a valence electron and ends with an atom having a complete outer shell structure of an inert gas.

The fourth period of the periodic table (d-block) consists of the transition elements.

The electron distribution into the energy levels of sublevels of atoms can be shown in any of the tree important electronic configuration.

Electronic configuration shows the sequence of filling electrons into the orbitals of the sublevels as guided by some principles.

The maximum number of electrons in the orbitals of sublevels are two for s-sublevel(one orbital) ; six for p-sublevel( three orbital); ten for d-sublevel ( five orbitals) and fourteen for f-sublevel( seven orbitals). This indicates that the maximum number of electrons in an orbital is two

In the Periodic table ,The sublevels with lower energies are filled up before those with higher energies. One important thing about this principle is that the sublevels do not fill up in numerical order. The pattern of filling is as follows:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f etc.

5 0

3 years ago

A first-order reaction (A → B) has a half-life of 25 minutes. If the initial concentration of A is 0.900 M, what is the concentr

Oksanka [162]

Answer:

0.6749 M is the concentration of B after 50 minutes.

Explanation:

A → B

Half life of the reaction = $t_{1/2}=25 minutes$