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vesna_86 [32]
3 years ago
14

The elements in groups 1a through 7a are

Chemistry
2 answers:
Semmy [17]3 years ago
4 0

1A alkali metals

2A alkali earth metals

3B-2B transition metals

7A halogens

8A noble gases

REY [17]3 years ago
3 0
The elements in<span> groups 1a through 7a are called d. representative elements. The periodic table is organized according to increasing order of the atomic number of the elements. Groups have similar properties while the period of the elements determines the valence electrons in the outer shells.</span>
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Two waves were analyzed with some high-tech instrumentation. The first wave was found to have a wavelength of 3 x 10 m and the s
a_sh-v [17]

Explanation:

The first wave was found to have a wavelength of 3 x 10⁵ m and the second wave had a wavelength of 3 x 10⁴ m

We need to find which wave have a higher frequency.

The relation between frequency and wavelength is given by :

c=f\lambda

Let f₁ and f₂ be the frequency of wave 1 and wave 2.

f_1=\dfrac{c}{\lambda_1}\\\\f_1=\dfrac{3\times 10^8}{3\times 10^5}\\\\=1000\ Hz

And

f_2=\dfrac{c}{\lambda_2}\\\\f_2=\dfrac{3\times 10^8}{3\times 10^4}\\\\=10000\ Hz

Hence, the wave having less wavelength will have higher frequency. The wave having wavelength 3 x 10⁴ m will have higher frequency.

8 0
3 years ago
what is the mass (in grams) of chlorine required to react with 10.0 g of sodium metal to produce sodium chloride?
Gnoma [55]

The mass of chlorine required to react with 10.0 g of sodium metal to produce sodium chloride is 15.26 g.

The balanced chemical reaction is :

<em>            2Na + Cl₂ → 2NaCl</em>

<em />

Given data :

Mass of sodium = 10.0 g

Number of moles of Na -

Number of moles = <u>  Given mass  </u>

                                    Molar mass

Number of moles = <u> 10.0 g</u> = 0.43 mol

                                  23 g

Comparing moles of Na and Cl₂ from the balanced chemical equation,

                                            Na        :        Cl₂

                                             2          :         1

                                             0.43     :        <u> 1 </u> x 0.43 = 0.215 mol

                                                                   2

Mass of chlorine gas :

          (molar mass of chlorine = 71 g)

Mass of chlorine = number of moles x molar mass

Mass = 0.215 mol x 71 g/mol

          = 15.26 g

To learn more about sodium and chlorine,

brainly.com/question/14588368

#SPJ4

7 0
1 year ago
The Environmental Protection Agency has determined that safe drinking
dmitriy555 [2]

Answer:

b) \bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}

The confidence interval for this case is given (6.21, 6.59)

So we can conclude at 95% of confidence that the true mean for the PH concentration is between 6.21 and 6.59 moles per liter

c) Since the confidence interval not contains the value 7 we reject the hypothesis that the true mean is equal to 7. And the same result was obtained with the t test for the true mean.

Explanation:

We assume that part a is test the claim. And we can conduct the following hypothesis test:

Null hypothesis: \mu =7

Alternative hypothesis \mu \neq 7

The statistic is to check this hypothesi is given by:

t = \frac{\bar X -\mu}{\frac{s}{\sqrt{n}}}

We know the following info from the problem:

\bar X = 6.4 , s=0.5, n =30

Replacing we got:

t = \frac{6.4-7}{\frac{0.5}{\sqrt{30}}}= -6.573

And the p value would be:

p_v= 2*P(Z

Since the p value is very low compared to the significance assumed of 0.05 we have enough evidence to reject the null hypothesis that the true mean is equal to 7 moles/liter

Part b

The confidence interval is given by:

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}

The confidence interval for this case is given (6.21, 6.59)

So we can conclude at 95% of confidence that the true mean for the PH concentration is between 6.21 and 6.59 moles per liter

Part c

Since the confidence interval not contains the value 7 we reject the hypothesis that the true mean is equal to 7. And the same result was obtained with the t test for the true mean.

6 0
3 years ago
An atom has 32 protons, 40 neutrons, and 32 electrons. What is the charge of the atom’s nucleus?
eimsori [14]
The charge is neutral.

To find the charge, subtract the number of electrons from the number of protons. Because they are the same, there is no charge.
8 0
3 years ago
Which identifies that a chemical reaction has occured ?
MaRussiya [10]
I believe the answer is  A. im not to sure though hoped this helped!
8 0
3 years ago
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