Animals with a nervous system show several more complex types of responses. These responses are called what responses

One of the emission spectral lines for Be31 has a wavelength of 253.4 nm for an electronic transition that begins in the state w

max2010maxim [7]

Explanation:

The given data is as follows.

$\lambda$ = 253.4 nm = $253.4 \times 10^{-9}m$ (as 1 nm = $10^{-9}$ )

$n_{1}$ = 5, $n_{2}$ = ?

Relation between energy and wavelength is as follows.

E = $\frac{hc}{\lambda}$

= $\frac{6.626 \times 10^{-34} Js \times 3 \times 10^{8} m/s}{253.4 \times 10^{-9}}$

= $0.0784 \times 10^{-17}$ J

= $7.84 \times 10^{-19} J$

Hence, energy released is $7.84 \times 10^{-19} J$ .

Also, we known that change in energy will be as follows.

$\Delta E = -2.178 \times (Z)^{2}[\frac{1}{n^{2}_{2}} - \frac{1}{n^{2}_{1}}$

where, Z = atomic number of the given element

$7.84 \times 10^{-19} J = -2.178 \times (4)^{2}[\frac{1}{n^{2}_{2}} - \frac{1}{(5)^{2}}$

$\frac{7.84 \times 10^{-19} J}{34.848} = \frac{1}{n^{2}_{2}} - \frac{1}{(5)^{2}}$

0.02 + 0.04 = $\frac{1}{n^{2}_{1}}$

$n_{1}$ = $\sqrt{\frac{1}{0.06}}$

= 4

Thus, we can conclude that the principal quantum number of the lower-energy state corresponding to this emission is n = 4.

4 0

2 years ago

Why do the two elements silver and iron have different properties?

Firdavs [7]

Elements in same group / family tend to have similar properties ( but not exactly the same). Since, iron and silver are in two different group / families, they have different properties.

Also, Silver and iron have different properties because they have different atomic structure. Having different atomic structure means bonding differently with other elements. So, they have different properties.

4 0

2 years ago

How many grams are in 2.0 x 10-5 moles of uranium?

victus00 [196]

Answer and explanation in pic

5 0

2 years ago

Be sure to answer all parts. Predict the effect of decreasing the temperature on the amounts of reactants in the following react

lianna [129]

Answer:

(a) The amounts of reactants decrease.

(b) The amounts of reactants decrease.

(c) The amounts of reactants decrease.

(d) the amounts of reactants increase.

Explanation:

Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

(a) C₂H₂(g) + H₂O(g) ⇌ CH₃CHO(g) ΔH°rxn = − 151 kJ.

Since, ΔH is a negative value, the reaction is exothermic reaction.

So, the reaction can be represented as:

C₂H₂(g) + H₂O(g) ⇌ CH₃CHO(g) + heat.

As the temperature is decreases, it is like that decreasing the concentration of products side, that shifts the reaction towards the right side (products side) to attain the equilibrium again. So, the amounts of reactants decrease.

So, the right choice is reaction is: The amounts of reactants decrease.

(b) CH₃CH₂OH(l) + O₂ (g) ⇌ CH₃CO₂H(l) + H₂O(g) ΔH°rxn = − 451 kJ.

Since, ΔH is a negative value, the reaction is exothermic reaction.

So, the reaction can be represented as:

CH₃CH₂OH(l) + O₂ (g) ⇌ CH₃CO₂H(l) + H₂O(g) + heat.

As the temperature is decreases, it is like that decreasing the concentration of products side, that shifts the reaction towards the right side (products side) to attain the equilibrium again. So, the amount of reactants decrease.

So, the right choice is reaction is: The amounts of reactants decrease.

(c) 2C₂H₄(g) + O₂(g) ⇌ 2CH₃CHO(g) (exothermic).

Since, the reaction is exothermic reaction.

So, the reaction can be represented as:

2C₂H₄(g) + O₂(g) ⇌ 2CH₃CHO(g) + heat.

As the temperature is decreases, it is like that decreasing the concentration of products side, that shifts the reaction towards the right side (products side) to attain the equilibrium again. So, the amounts of reactants decrease.

So, the right choice is reaction is: The amounts of reactants decrease.

(d) N₂O₄(g) ⇌ 2NO₂(g) (endothermic).

For endothermic reaction, it can be represented as:

N₂O₄(g) + heat ⇌ 2NO₂(g)

As the temperature is decreased, it is like that decreasing the concentration of reactants side, that shifts the reaction towards the lift side (reactants side) to attain the equilibrium again. So, the amounts of reactants increase.

So, the right choice is reaction is: the amounts of reactants increase.

3 0

2 years ago

How many grams of CaF2 are present in 1.25 L of a 0.15 M solution of CaF2? How do I find the grams I am confused on that part?

dybincka [34]

Answer:

Mass = 14.64 g

Explanation:

Given data:

Volume of solution = 1.25 L

Molarity of Solution = 0.15 M

Mass of CaF₂ = ?

Solution:

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

We will calculate the number of moles of CaF₂ and then determine the mass by using number of moles.

0.15 M = number of moles of solute / 1.25 L

number of moles of solute = 0.15 M × 1.25 L

number of moles of solute = 0.1875 mol/L × L

number of moles of solute = 0.1875 mol

Mass in gram:

Mass = number of moles × molar mass

Mass = 0.1875 mol ×78.07 g/mol

Mass = 14.64 g

7 0

2 years ago