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3 years ago

. Why do carpenters use a screw instead of nails to join two pieces of wood?

2 answers:

7 0

Screws have phenomenal tensile strength which is far greater than nails. Screws build a tight adhesion between two pieces of wood.

Nails are used for joints, because even after multiple twists the wood at the joints will remain together when nails are used. But a screw will come off after a single twist, if screws are used to hold wood at the joints.

For any static wood work screws are better than nails because of their tensile strength.

Nataliya [291]3 years ago

5 0

Carpenters use nails instead of screws. If that isnt the answer you are looking for than another answer would be that screws hold better than nails. When you screw wood together they don't slide or turn sideways like when you nail wood together. When they are nailed together you can turn the two pieces of wood while they are stuck.

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(a) the characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. combustio

ella [17]

By stoichiometry and assume that:

CxH2xOy + zO2 -> xCO2 + xH2O

<span>
CO2: 9.48/44 = 0.215 mmol
H2O: 3.87/18 = 0.215 mmol
mass of C = 0.215 * 12 = 2.58 mg
mass of H = 0.215 * 2 * 1 = 0.43 mg
mass of O in ethylbutyrate = 4.17 - 2.58 - 0.43 = 1.11 mg
So C/O = 2.58/1.11 ≈ 3 </span>

8 0

3 years ago

Read 2 more answers

How many atoms and ions does nickel oxide have?

Alex73 [517]

Answer: 1 atom

Explanation:

The loss of the remaining valence electron results in an ion with a +2 charge. The proper way of noting the charges on these ions is to use the systematic name for each ion, nickel (I) for the +1 ion and nickel (II) for the +2 ion.

4 0

3 years ago

What is the mass of 4.99×1021 platinum atoms?

charle [14.2K]

Answer:

$\boxed {\boxed {\sf 1.62 \ g \ Pt}}$

Explanation:

We are asked to find the mass of a number of platinum (Pt) atoms.

<h3>1. Convert Atoms to Moles </h3>

First, we convert atoms to moles using Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are platinum atoms.

We will convert using dimensional analysis so we set up a ratio using the information we know (6.022 × 10²³ platinum atoms in 1 mole of platinum).

$\frac {6.022 \times 10^{23} \ atoms \ Pt}{ 1 \ mol \ Pt}$

We are converting 4.99 ×10²¹ atoms of Pt to moles of Pt, so we multiply by this value.

$4.99 \times 10^{21} \ atoms \ Pt *\frac {6.022 \times 10^{23} \ atoms \ Pt}{ 1 \ mol \ Pt}$

Flip the ratio so the units of atoms of platinum cancel.

$4.99 \times 10^{21} \ atoms \ Pt *\frac { 1 \ mol \ Pt}{6.022 \times 10^{23} \ atoms \ Pt}$

$4.99 \times 10^{21} *\frac { 1 \ mol \ Pt}{6.022 \times 10^{23}}$

$\frac { 4.99 \times 10^{21}}{6.022 \times 10^{23}} \ mol \ Pt$

Divide.

$0.008286283627 \ mol \ Pt$

<h3>2. Convert Moles to Grams </h3>

Next, we convert moles to grams using the molar mass. This is the mass of 1 mole of a substance. This is found on the Periodic Table because it is equivalent to the atomic mass, but the units are grams per mole instead of atomic mass units. Look up platinum's molar mass.

Pt: 195.08 g/mol

Set up another ratio using this new information (195.08 grams of Pt in 1 mole of Pt).

$\frac {195.08 \ g \ Pt}{ 1 \ mol \ Pt}$

Multiply by the number of moles we just calculated.

$0.008286283627 \ mol \ Pt*\frac {195.08 \ g \ Pt}{ 1 \ mol \ Pt}$

The units of moles of platinum cancel.

$0.008286283627*\frac {195.08 \ g \ Pt}{ 1 }$

$0.008286283627* {195.08 \ g \ Pt}$

$1.61648821\ g \ Pt$

<h3>3. Round</h3>

The original measurement of atoms ( 4.99 ×10²¹ ) has 3 significant figures, so our answer must have the same. For the number we found, that is the hundredth place. The 6 in the thousandth place tells us to round the 1 up to a 2.

$1.62 \ g \ Pt$

There are approximately <u>1.62 grams of platinum</u> in 4.99 ×10²¹ atoms of platinum.

8 0

3 years ago

To which period does an element belong if it has its 3d orbitals filled

kotegsom [21]

fourth period

The third period is similar to the second, except the 3s and 3p sublevels are being filled. Because the 3d sublevel does not fill until after the 4s sublevel, the fourth period contains 18 elements, due to the 10 additional electrons that can be accommodated by the 3d orbitals.

3 0

3 years ago

2. You water three sunflower plants with salt water. Each plant receives a different

wlad13 [49]

Answer:

Independent variable, is the amount of salt water received by each plant

Dependent variable, is the height of each plant

Control group, is the fourth plant that received pure water.

Note: The question is incomplete. The complete question is as follows: For the following experiments, define the independent variable (IV), dependent variable (DV) and control group (CG).

2. You water three sunflower plants with salt water. Each plant receives a different concentration of salt solutions. A fourth plant receives pure water. After a two-week period, the height is measured.

Explanation:

Independent variable: An independent variable is a variable that an experimenter changes or controls and which has a direct effect on the dependent variable.

In the experiment above, the independent variable is the amount of salt water received by each plant because it is under the control of the experimenter and also is thought to have a direct effect on the height of plants.

Dependent variable: A dependent variable is a variable that is being measured or studied in an experiment, and it depends on the independent variable for its results.

The height of the plants is the dependent variable as it depends on the amount of salt water the plant receives.

Control group: The control group is the group in an experiment or study that does not receive the treatment as the other groups being studied and as such, is not influenced by the independent variable. Therefore, it is used as a standard for the other groups under study.

In this experiment, the control group is the fourth plant that received pure water.

3 0

3 years ago