Identify the total number of molecules in the chemical formula: 6CH4 a 6 b 10 c 24 d 30

On the Periodic Table, which elements are predominantly (mostly) gases with low densities?

aliya0001 [1]

I’m sorry if I wasted your time but I think it’s alkali metals but I’m
Not sure

5 0

3 years ago

What species is undergoing reduction in the following reaction? NO3-(aq) + 4Zn(s) + 7OH-(aq) + 6H2O(l) → 4Zn(OH)42-(aq) + NH3(aq

RUDIKE [14]

Zn because it gains electrons

4 0

4 years ago

Who found the periodic table

Whitepunk [10]

Answer: Dmitri Mendeleev

Explanation: He invented it, since he wanted to arrange all the elements.

5 0

3 years ago

What is the wavelength of microwaves of 3.0 × 10^9 Hz frequency? a. 0.050 m c. 0.10 m b. 0.060 m d. 0.20 m

Alex777 [14]

Hello!

We have the following data:

f (radiation frequency) = 3.0 × 10^9 Hz

v (speed of light) = 3*10^8\:m/s

λ (wavelength) = ? (in m)

Let's find the wavelength, let's see:

$f = \dfrac{v}{\lambda}$

$3.0*10^9 = \dfrac{3*10^8}{\lambda}$

$\lambda = \dfrac{3*10^8}{3*10^9}$

$\lambda = 1*10^{8-9}$

$\lambda = 1*10^{-1}$

$\boxed{\boxed{\lambda = 0.1\:m}}\end{array}}\qquad\checkmark$

Answer:

c. 0.10 m

________________

I Hope this helps, greetings ... DexteR! =)

7 0

3 years ago

A mixture of 65 percent N2 and 35 percent CO2 gases (on a mass basis) enters the nozzle of a turbojet engine at 60 psia and 1400

kirza4 [7]

Answer:

a. 969.1 R

b. 2237 ft/s

Explanation:

First the apparent specific heats are determined from the mass fractions of the gases:

$c_{p} &=\left(\mathrm{mf} c_{p}\right)_{\mathrm{N}_{2}}+\left(\mathrm{mf} c_{p}\right) \mathrm{CO}_{2} \\
&=(0.65 \cdot 0.248+0.35 \cdot 0.203) \frac{\mathrm{Btu}}{\mathrm{lbm} \mathrm{R}} \\
&=0.232 \frac{\mathrm{Btu}}{\mathrm{lbmR}} \\
c_{v} &=\left(\mathrm{mf} c_{v}\right)_{\mathrm{N}_{2}}+\left(\mathrm{mf} c_{v}\right)_{\mathrm{CO}_{2}} \\
&=(0.65 \cdot 0.177+0.35 \cdot 0.158) \frac{\mathrm{Btu}}{\mathrm{lbmR}} \\
&=0.170 \frac{\mathrm{Btu}}{\mathrm{lbmR}}$

The isentropic coefficient then is:

$k &=\frac{c_{p}}{c_{v}} \\
&=\frac{0.232}{0.17} \\
&=1.365$

The final temperature is determined from the isentropic nozzle efficiency relation:

$T_{2} &=T_{1}-\eta_{N}\left(T_{1}-T_{2 s}\right) \\
&=T_{1}\left(1-\eta_{N}\left(1-\left(\frac{P_{2}}{P_{1}}\right)^{(k-1) / k}\right)\right) \\
&=1400\left(1-0.88\left(1-\left(\frac{800}{100}\right)^{(1.365-1) / 1.365}\right)\right) \mathrm{R} \\
&=969.1 \mathrm{R}$

b. The outlet velocity is determined from the energy balance:

$h_{1} &+\frac{v_{1}^{2}}{2}=h_{2}+\frac{v_{2}^{2}}{2} \\
v_{2} &=\sqrt{2 c_{p}\left(T_{1}-T_{2}\right)} \\
&=\sqrt{2 \cdot 0.232(1400-969.2) \cdot 25037} \frac{\mathrm{ft}}{\mathrm{s}} \\
&=2237 \frac{\mathrm{ft}}{\mathrm{s}}$

7 0

3 years ago