1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Levart [38]
3 years ago
10

1. Which two groups of elements in the periodic table are the most reactive?(1 point) A) alkali metals and halogens B) alkaline

earth metals and halogens C)halogens and noble gases D)noble gases and alkali metals 2. Use the periodic table to answer the question. Which statement about nitrogen (N) and phosphorus (P) is correct? (1 point) A)They have the same number of valence electrons. B)They have the same number of electron shells. C)They are both classified as halogens. D)They are both inert. 3. Which property do transition metals have in common?(1 point) A)They usually have low densities. B)They are usually very soft. C)They are usually very reactive. D)They usually have high melting points. 4. Neon and argon are both in Group 18 of the periodic table. Which property do they most likely share?(1 point) A)low or no reactivity B)silver color C)strong odor D)metallic texture 5. A scientist studies an element that has seven electrons in its outer shell, is fairly toxic, and is highly reactive. To which group of the periodic table does this element belong?(1 point) A) 17 B) 1 C) 18 D) 2 PLEASEE HELP I NEED IT DONE BY TMR
Chemistry
1 answer:
tatyana61 [14]3 years ago
4 0

Answer:

Explanation:

1) alkali metals and halogens as alkalis have 1 electron they need to get rid of in order to gain a full outer shell of electrons and the halogens have to gain 1 electron.

2) they have the same number of electrons on the outer shells

3)they usually have high melting points

4) low or no reactivity

5) group 7

You might be interested in
Here is a more complex redox reaction involving the dichromate ion in acidic solution: 3N O 2 − + 8H + + C r 2 O 7 2− → 3N O 3 −
Fantom [35]

Answer:

NO2- is the reducing agent.

Cr2O7_2- is the oxidizing agent.

H+ is neither

Explanation:

Reduction is the gain in electron. A chemical specie that undergoes reduction is called the oxidizing agent.

Oxidation is simply the loss in electrons. A chemical specie that undergoes oxidation is called the reducing agent.

Let us look at the species.

The first specie is the NO2-. In this specie, the oxidation number of nitrogen changed from +3 to +5 in NO3-. Thus we can see that there is more loss of electron to have caused an increase in the oxidation number positively. This shows an oxidation. Hence, NO2- is the reducing agent.

Let us look at the chromium. We can see that the oxidation number of chromium changed from +7 to +3.

Now we can see that it is a decrease and hence, it is a gain of electron and thus it is reduction. This means the first chromium specie is the oxidizing agent.

The hydrogen ion is simply placed there to balance the ions and hence it is neither the oxidizing nor the reducing agent.

4 0
3 years ago
Why do atoms move at different speeds depending on whether they are in liquids or solids.
bekas [8.4K]
<span>In a solid the atoms are tightly packed together and vibrate in place, in a liquid the atoms are loosely packed together and can move past each other,
 
extra: and in a gas the atoms are far apart and move freely and </span><em>
</em><em>
</em>
6 0
3 years ago
A flask contains a mixture of hydrogen gas and water vapor at STP. If the pressure of the water vapor is 19.5 mmHg, then what is
horrorfan [7]

Answer:

I would say A but not sure

Explanation:

7 0
2 years ago
How can an invasive species like weeds affect crops on a farm?
Hoochie [10]

Answer:

E

Explanation:

All of the above

3 0
3 years ago
One question please help!
Agata [3.3K]
<span>1 trial : you have nothing to compare the result with - you don't know if it's a mistake.
2 trials : you can compare results - if very different, one may have gone wrong, but which one?
3 trials : if 2 results are close and 3rd far away, 3rd probably unreliable and can be rejected.

******************************

First calculate the enthalpy of fusion. M, C and m,c = mass and specific heat of calorimeter and water; n, L = mass and heat of fusion of ice; T = temperature fall.

L = (mc+MC)T/n.

c=4.18 J/gK. I assume calorimeter was copper, so C=0.385 J/gK.

1. M = 409g, m = 45g. T = 22c, n = 14g
L = (45*4.18+409*0.385)*22/14 = 543.0 J/g.

2. M = 409g, m = 49g, T = 20c, n = 13g
L = (49*4.18+409*0.385)*20/13 = 557.4 J/g.

3. M = 409g, m = 54g, T = 20c, n = 14g
L = (54*4.18+409*0.385)*20/14 = 547.4 J/g.

(i) Estimate error in L from spread of 3 results.
Average L = 549.3 J/g.
average of squared differences (variance) = (6.236^2+8.095^2+1.859^2)/3 = 35.96
standard deviation = 5.9964
standard error = SD/(N-1) = 5.9964/2 = 3 J/g approx.

% error = 3/547 x 100% = 0.5%.

(ii) Estimate error in L from accuracy of measurements:
error in masses = +/-0.5g
error in T = +/-0.5c

For Trial 3
M = 409g, error = 0.5g
m = 463-409, error = sqrt(0.5^2+0.5^2) = 0.5*sqrt(2)
n =(516-463)-(448-409)=14, error = 0.5*sqrt(4) = 1.0g
K = (mc+MC)=383, error = sqrt[2*(0.5*4.18)^2+(0.5*0.385)^2] = 2.962

L = K*T/n
% errors are
K: 3/383 x 100% = 0.77
T: 0.5/20 x 100% = 2.5
n: 1.0/14 x 100% = 7.14

% errors in K and T are << error in n, so we can ignore them.
% error in L = same as in n = 7% x 547.4 = 40 (always round final error to 1 sig fig).

*************************************

The result is (i) L= 549 +/- 3 J/g or (ii) L = 550 +/- 40 J/g.
Both are very far above accepted figure of 334 J/g, so there is at least one systematic error in the experiment or the calculations.
eg calorimeter may not be copper, so C is not 0.385 J/gK. (If it was polystyrene, which absorbs/ transmits little heat, the effective value of C would be very low, reducing L.)
Using +/- 40 is probably best (more cautious).
However, the spread in the actual results is much smaller; try to explain this discrepancy - eg
* measurements were "fiddled" to get better results; other Trials were made but only best 3 were chosen.
* measurements were more accurate than I assumed (eg masses to nearest 0.1g but rounded to 1g when written down).

Other sources of error:
L=(mc+MC)T/n is too high, so n (ice melted) may be too small, or T (temp fall) too high - why?
* it is suspicious that all final temperatures were 0c - was this actually measured or just guessed? a higher final temp would reduce L.
* we have assumed initial and final temperature of ice was 0c, it may actually have been colder, so less ice would melt - this could explain small values of n
* some water might have been left in container when unmelted ice was weighed (eg clinging to ice) - again this could explain small n;
* poor insulation - heat gained from surroundings, melting more ice, increasing n - but this would reduce measured L below 334 J/g not increase it.
* calorimeter still cold from last trial when next one started, not given time to reach same temperature as water - this would reduce n.
Hope This Helps :)
</span>
3 0
3 years ago
Other questions:
  • What sublevels are contained in the hydrogen atoms first four energy levels what orbitals are related to each?
    9·1 answer
  • In an experiment, potassium chlorate decomposed according to the following chemical equation.
    8·1 answer
  • Which one of the following types of rock would weather the fastest
    13·1 answer
  • Use the Earth's Energy Budget diagram to answer the question. Based on the diagram, less solar energy that reaches Earth is ____
    5·1 answer
  • How many more times intense is an earthquake that measures 8 on the Richter scale than an earthquake that measures 5? Explain yo
    15·2 answers
  • Which of the changes of state requires the removal of energy?
    7·2 answers
  • A chemical engineer must report the average volume of a certain pollutant produced by the plants under her supervision. Here are
    10·1 answer
  • What is the expected mass (in kg) of a 10 over 5 B isotope? 1 proton = 1.6726 × 10-27 kg 1 neutron = 1.6749 × 10-27 kg A.1.67 ×
    12·1 answer
  • Explain why smell is a physical property?
    8·1 answer
  • How many protons does an atom of gold have?
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!