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3 years ago

PLEASE HELP 8TH GRADE SCIENCE. which of the following is the correct Lee abbreviated SI unit describing the mass of an object

Chemistry

2 answers:

Licemer1 [7]3 years ago

6 0

Lucky guess dont put as a answer c.m

melamori03 [73]3 years ago

3 0

D. kg b/c to know the mass of an object you must measure it in grams

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Identify fossil types match each each type of fossil to its description

dem82 [27]

Well we need to see the fossil

4 0

3 years ago

Read 2 more answers

Sodium hydroxide reacts with aluminum and water to produce hydrogen gas: 2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H

lianna [129]

Answer:

The mass of hydrogen gas formed is 0.205 grams

Explanation:

Step 1: Data given

Mass of 1.83 grams of Al

Mass of NaOH = 4.30 grams

Molar mass of Al = 26.98 g/mol

Molar mass of NaOH = 40 g/mol

Step 2: The balanced equation:

2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H2(g)

Step 3: Calculate moles of Al

Moles Al = mass Al / Molar mass Al

Moles Al = 1.83 grams / 26.98 g/mol

Moles Al = 0.0678 moles

Step 4: Calculate moles of NaOH

Moles NaOH = 4.30 grams / 40 g/mol

Moles NaOH = 0.1075 moles

Step 5: Calculate limiting reactant

For 2 moles of Al, we need 2 moles of NaOH

Aluminium is the limiting reactant. It will completely be consumed ( 0.0678 moles)

NaOH is in excess. There will react 0.0678 moles

There will remain 0.1075 - 0.0678 = 0.0397 moles

Step 6: Calculate moles of hydrogen

For 2 moles of Al, we need 2 moles of NaOH, to produce 3 moles of hydrogen

For 0.0678 moles of Al, there is produced 0.0678 *3/2 = 0.1017 moles of H2

Step 7: Calculate mass of H2

Mass of H2 = Moles H2 * Molar mass of H2

Mass of H2 = 0.1017 moles * 2.02 g/mol

Mass of H2 = 0.205 grams

The mass of hydrogen gas formed is 0.205 grams

6 0

3 years ago

All three of the phosphorus-fluorine single bonds in pf3 are polar. in which direction should the polarity arrows point?

nydimaria [60]

One of the causes of polarity is the unequal forces of the dipole forces due to differences in electronegativity. The more electronegative molecule tend to attract electrons, hence the polarity arrows point towards it. The electronegativity of Phosphorus and Fluorine is 2.19 and 3.98, respectively. Thus, it points outward towards the fluorine atoms.

3 0

3 years ago

How many CaF are in a 1.7x10^25 please I need help fast!!

Gemiola [76]

<h3>Answer:</h3>

28 mol CaF

<h3>General Formulas and Concepts:</h3>

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Chemistry

Atomic Structure

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

Using Dimensional Analysis

<h3>Explanation:</h3>

Step 1: Define

[Given] 1.7 × 10²⁵ molecules CaF

[Solve] moles CaF

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

[DA] Set up: $\displaystyle 1.7 \cdot 10^{25} \ molecules \ CaF(\frac{1 \ mol \ CaF}{6.022 \cdot 10^{23} \ molecules \ CaF})$
[DA] Multiply/Divide [Cancel out units]: $\displaystyle 28.2298 \ moles \ CaF$

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

28.2298 mol CaF ≈ 28 mol CaF

7 0

3 years ago

how does getting funding from the government affect scientific research?? a- the government helps the scientist decide what rese

sertanlavr [38]

Answer:

d- Scientists have to follow government rules made to protect people.

Explanation:

Scientific research fosters our understanding of the world around us. It helps people to learn to promote critical thought and problem-solving. Although there may not be an immediate practical use of the research, in the long term the study could benefit humanity. Scientific research is the product of creative ideas and collaborative communication that the proper role of government is often restricted to funding the research. The role of the government is to perform its reasonable and valid duties of defending human rights and enhancing the independence of the human.

4 0

3 years ago