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3 years ago

14

An astronomer wants to study celestial objects with the shortest wavelengths. What kind of telescope should the astronomer use f

or this task?

1 answer:

Leni [432]3 years ago

8 0

Answer:

telescope

Explanation:

i took the test

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A laboratory instructor gives a sample of amino-acid powder to each of four students, I, II, III, and IV, and they weigh the sam

Dovator [93]

According to the calculation, set I is both the most accurate and most precise.

Exactness is a quality or state of being precise. 2a: comparison accuracy sense: the degree of precision with which an action is carried out or a measurement expressed 2b. The novel was fact-checked for historical authenticity. 2a: conformance to truth, to a standard, or to a model: exactness It is impossible to estimate the number of casualties with accuracy. Let's calculate the precision for the fourth set, considering $AV_I_V=8.56g$

Δ1 = ∣(8.41−8.56)∣ g=0.15 g

Δ2 = (8.72−8.56) g=0.16 g

Δ3 = ∣(8.55−8.56)∣ g=0.01 g

Therefore: $\triangle_I = \frac{\triangle1+\triangle2+\triangle3}{3} = 0.107g$

Learn more about accuracy and precision here:

brainly.com/question/28289139

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5 0

1 year ago

The standard enthalpy change for the following reaction is 873 kJ at 298 K.

Flura [38]

Answer: - 436.5 kJ.

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation.

The given chemical reaction is,

$2KCl(s)\rightarrow 2K(s)+Cl_2(g)$ $\Delta H_1=873kJ$

Now we have to determine the value of $\Delta H$ for the following reaction i.e,

$K(s)+\frac{1}{2}Cl_2(g)\rightarrow KCl(s)$ $\Delta H_2=?$

According to the Hess’s law, if we divide the reaction by half then the $\Delta H$ will also get halved and on reversing the reaction , the sign of enthlapy changes.

So, the value $\Delta H_2$ for the reaction will be:

$\Delta H_2=\frac{1}{2}\times (-873kJ)$

$\Delta H_2=-436.5kJ$

Hence, the value of $\Delta H_2$ for the reaction is -436.5 kJ.

8 0

3 years ago

If 16.00 g of O₂ reacts with 80.00 g NO, how many the excess reactant are left over? (enter only the value, round to whole numbe

pishuonlain [190]

Answer:

50

Explanation:

We will need a balanced equation with masses, moles, and molar masses of the compounds involved.

1. Gather all the information in one place with molar masses above the formulas and masses below them.

Mᵣ: 30.01 32.00 46.01

2NO + O₂ ⟶ 2NO₂

Mass/g: 80.00 16.00

2. Calculate the moles of each reactant

$\text{moles of NO} = \text{80.00 g NO} \times \dfrac{\text{1 mol NO}}{\text{30.01 g NO}} = \text{2.666 mol NO}\\\\\text{moles of O}_{2} = \text{16.00 g O}_{2} \times \dfrac{\text{1 mol O}_{2}}{\text{32.00 g O}_{2}} = \text{0.5000 mol O}_{2}$

3. Calculate the moles of NO₂ we can obtain from each reactant

From NO:

The molar ratio is 2 mol NO₂:2 mol NO

$\text{Moles of NO}_{2} = \text{2.333 mol NO} \times \dfrac{\text{2 mol NO}_{2}}{\text{2 mol NO}} = \text{2.333 mol NO}_{2}$

From O₂:

The molar ratio is 2 mol NO₂:1 mol O₂

$\text{Moles of NO}_{2} = \text{0.5000 mol O}_{2}\times \dfrac{\text{2 mol NO}_{2}}{\text{1 mol Cl}_{2}} = \text{1.000 mol NO}_{2}$

4. Identify the limiting and excess reactants

The limiting reactant is O₂ because it gives the smaller amount of NO₂.

The excess reactant is NO.

5. Mass of excess reactant

(a) Moles of NO reacted

The molar ratio is 2 mol NO:1 mol O₂

$\text{Moles reacted} = \text{0.500 mol O}_{2} \times \dfrac{\text{2 mol NO}}{\text{1 mol O}_{2}} = \text{1.000 mol NO}$

(b) Mass of NO reacted

$\text{Mass reacted} = \text{1.000 mol NO} \times \dfrac{\text{30.01 g NO}}{\text{1 mol NO}} = \text{30.01 g NO}$

(c) Mass of NO remaining

Mass remaining = original mass – mass reacted = (80.00 - 30.01) g = 50 g NO

5 0

3 years ago

10. Air is a homogenous mixture of gases. Oxygen is 20% by volume of air typically. What

raketka [301]

Answer:

893 moles

Explanation:

An ideal gas at STP occupies 22.4 liters. Calculating Oxygen as if it were an ideal gas there are . 893 moles of Oxygen in 20.0 liters.

3 0

3 years ago

Hợp chất nào có khả năng là hợp chất ion cao nhất ?<br>A Al2O3<br>B ScCl3<br>C NO2<br>D CCl4

Rzqust [24]

Answer:

B

Explanation:

hợp chất nào có khả năng là hợp chất ion cao nhất ?

A Al2O3?

B

7 0

3 years ago