Which of the following measurements has FOUR significant figures?

What is 694,563,239 rounded to the nearest thousand

lina2011 [118]

694,563,239 rounded to the nearest thousand is 694,563.

It's because the first digit from the right is for ones, second for tens, third for hundreds and fourth for thousands and that's the one that we should take a closer look at. You can round it either to 3 or 4, depends on the digit of hundreds. In this case 3239 is clearly closer to 3000 than 4000, that's why we round it to 694,563, not 694,564.

6 0

3 years ago

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What represents a community? pond B a snail snails D snails, guppies and plants

OLga [1]

D snails, guppies and plants. The community should be diverse and have lots of biodiversity.

7 0

3 years ago

An iron has a net charge of 3+. If this job has 8 protons, how many electrons does it have

kati45 [8]

Answer:

5 electrons

Explanation:

When an atom loses are gain the electrons ions are formed.

There are two types of ions.

Anion

Cation

1 = Anion

It is formed when an atom gain the electrons. when atom gain electron negative charge is created on atom. For example.

X + e⁻ → X⁻

2= Cation

It is formed when an atom loses the electrons. when atom lose electron positive charge is created on atom. For example.

X → X⁺ + e⁻

When an atom loses three electrons +3 charge is created. If this atom have 8 protons it means there were 8 electrons too. When it lost three electrons then remaining number of electrons are 5.

X → X³⁺ + 3e⁻

4 0

3 years ago

Suppose a 250. mL flask is filled with 0.30 mol of N_2 and 0.70 mol of NO. The following reaction becomes possible:N_2(g) +O2 →

Inessa [10]

Answer:

0.4 M

Explanation:

Equilibrium occurs when the velocity of the formation of the products is equal to the velocity of the formation of the reactants. It can be described by the equilibrium constant, which is the multiplication of the concentration of the products elevated by their coefficients divided by the multiplication of the concentration of the reactants elevated by their coefficients. So, let's do an equilibrium chart for the reaction.

Because there's no O₂ in the beginning, the NO will decompose:

N₂(g) + O₂(g) ⇄ 2NO(g)

0.30 0 0.70 Initial

+x +x -2x Reacts (the stoichiometry is 1:1:2)

0.30+x x 0.70-2x Equilibrium

The equilibrium concentrations are the number of moles divided by the volume (0.250 L):

[N₂] = (0.30 + x)/0.250

[O₂] = x/0.25

[NO] = (0.70 - 2x)/0.250

K = [NO]²/([N₂]*[O₂])

K = $\frac{(\frac{0.70 -2x}{0.250})^2 }{\frac{0.30+x}{0.250}*\frac{x}{0.250} }$

7.70 = (0.70-2x)²/[(0.30+x)*x]

7.70 = (0.49 - 2.80x + 4x²)/(0.30x + x²)

4x² - 2.80x + 0.49 = 2.31x + 7.70x²

3.7x² + 5.11x - 0.49 = 0

Solving in a graphical calculator (or by Bhaskara's equation), x>0 and x<0.70

x = 0.09 mol

Thus,

[O₂] = 0.09/0.250 = 0.36 M ≅ 0.4 M

3 0

3 years ago

Iron reacts with cl2 according to the equation 2 fe(s) + 3 cl2(g) ? 2 fecl3(s). how many moles of cl2 is needed to react with 4.

IceJOKER [234]

2Fe + 3Cl₂ ---> 2FeCl₃

4.4mol of Fe, you have a 2:3 ratio of Fe to Cl₂ so divide 4.4/2 = 2.2 and multiply by three 2.2 x 3 = 6.6mol of Cl₂

hope that helps :)

8 0

3 years ago

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