Burning magnesium. Mg + O2 →

PLEASE HELP! List the 5 basic steps of the scientific method in order

Kruka [31]

Step 1: Ask a question or identify a problem. ...Step 2: Background research. ...Step 3: Form a hypothesis. ...Step 4: Experiment and observe. ...Step 5: Draw a conclusion.

3 0

3 years ago

Control activities are performed within processes (e.g., segregation of duties required in processing cash receipt transactions)

galina1969 [7]

Answer:

a. True

Explanation:

The control objectives seek to support the fulfillment of the critical factors of business success, in order to finally support the achievement of the institutional objectives, on this the CITI is based

It is very important to clearly identify the relationships of the control objectives with other internal control elements such as:

· Critical success factors receive direct support from control objectives to support compliance.

· The control objectives are made up of control goals, which allow them to have a more detailed perspective of the control objectives and at the same time facilitate the evaluation of their compliance.

CITI CONCEPT:

It is the set of administration elements that a company establishes in a coordinated way so that the use of information technology resources effectively supports the institutional objectives of the company

6 0

3 years ago

A tank contains 90 kg of salt and 2000 L of water. Pure water enters a tank at the rate 6 L/min. The solution is mixed and drain

sashaice [31]

Answer:

a) 90 kg

b) 68.4 kg

c) 0 kg/L

Explanation:

Mass balance:

$-w=\frac{dm}{dt}$

w is the mass flow

m is the mass of salt

$-v*C=\frac{dm}{dt}$

v is the volume flow

C is the concentration

$C=\frac{m}{V+(6-3)*L/min*t}$

$-v*\frac{m}{V+(6-3)*L/min*t}=\frac{dm}{dt}$

$-3*L/min*\frac{m}{2000L+(3)*L/min*t}=\frac{dm}{dt}$

$-3*L/min*\frac{dt}{2000L+(3)*L/min*t}=\frac{dm}{m}$

$-3*L/min*\int_{0}^{t}\frac{dt}{2000L+(3)*L/min*t}=\int_{90kg}^{m}\frac{dm}{m}$

$-[ln(2000L+3*L/min*t)-ln(2000L)]=ln(m)-ln(90kg)$

$-ln[(2000L+3*L/min*t)/2000L]=ln(m/90kg)$

$m=90kg*[2000L/(2000L+3*L/min*t)]$

a) Initially: t=0

$m=90kg*[2000L/(2000L+3*L/min*0)]=90kg$

b) t=210 min (3.5 hr)

$m=90kg*[2000L/(2000L+3*L/min*210min)]=68.4kg$

c) If time trends to infinity the division trends to 0 and, therefore, m trends to 0. So, the concentration at infinit time is 0 kg/L.

6 0

3 years ago

26.6 mL of 2.50 M stock solution of sucrose is diluted to 50.0 mL. A 16.0 mL sample of the resulting solution is then diluted to

frozen [14]

Answer:

In the final solution, the concentration of sucrose is 0.126 M

Explanation:

Hi there!

The number of moles of solute in the volume taken from the more concentrated solution will be equal to the number of moles of solute in the diluted solution. Then, the concentration of the first solution can be calculated using the following equation:

Ci · Vi = Cf · Vf

Where:

Ci = concentration of the original solution

Vi = volume of the solution taken to prepare the more diluted solution.

Cf = concentration of the more diluted solution.

Vf = volume of the more diluted solution.

For the first dillution:

26.6 ml · 2.50 M = 50.0 ml · Cf

Cf = 26.6 ml · 2.50 M / 50.0 ml

Cf = 1.33 M

For the second dilution:

16.0 ml · 1.33 M = 45.0 ml · Cf

Cf = 16.0 ml · 1.33 M / 45.0 ml

Cf = 0.473 M

For the third dilution:

20.0 ml · 0.473 M = 75.0 ml · Cf

Cf = 20.0 ml · 0.473 M / 75.0 ml

Cf = 0.126 M

In the final solution, the concentration of sucrose is 0.126 M

7 0

3 years ago

Which of the following numbers count as exact numbers and do not count when determining significant figures in a calculation? 1.

rewona [7]

Answer :

(1) Density do not count as exact number.

(2) Volume count as exact number.

(3) Length count as exact number.

(4) Speed do not count as exact number.

(5) Number count as exact number.

(6) Mass do not count as exact number.

Explanation :

Exact numbers : It is a defined or integer value which comes from counting numbers of objects.

They have an infinite number of significant figures.

For example : 12 eggs in a dozen, 1000 g in a kilogram and 2.54 cm in an inch.

Now we have to determine the following numbers count as exact numbers.

(1) Density : 3.7 g/mL

Density do not count as exact number.

(2) Volume : 1000 mL/L

Volume count as exact number.

(3) Length : 2.54 cm/in

Length count as exact number.

(4) Speed : 65.2 km/hr

Speed do not count as exact number.

(5) Number : 14 aardvarks

Number count as exact number.

(6) Mass : 38.741 g

Mass do not count as exact number.

4 0

3 years ago