This question tests knowledge about the common oxidation reactions of metals, specifically silver and copper, when exposed to the atmosphere. These reactions lead to the formation of compounds on their surfaces, causing a change in their appearance or color.
Oxidation of Silver: When silver objects are exposed to air, they react with hydrogen sulfide (\(\text{H}_2\text{S}\)) gas present in the atmosphere. This reaction forms silver sulfide (\(\text{Ag}_2\text{S}\)), which is black in color. This phenomenon is commonly known as tarnishing.
\[ 2\text{Ag(s)} + \text{H}_2\text{S(g)} \rightarrow \text{Ag}_2\text{S(s)} + \text{H}_2\text{(g)} \]
Therefore, silver changes its color to black on oxidation.
Oxidation of Copper: When copper objects are exposed to moist air for a prolonged period, they react with carbon dioxide (\(\text{CO}_2\)) and moisture (\(\text{H}_2\text{O}\)) in the atmosphere. This reaction forms a green layer of basic copper carbonate (\(\text{CuCO}_3 \cdot \text{Cu(OH)}_2\)). This process is often seen on old copper statues or roofs.
\[ \text{2Cu(s)} + \text{H}_2\text{O(g)} + \text{CO}_2\text{(g)} + \text{O}_2\text{(g)} \rightarrow \text{CuCO}_3 \cdot \text{Cu(OH)}_2\text{(s)} \]
Therefore, copper changes its color to green on oxidation.
Based on these reactions, silver changes to black and copper changes to green.
B) black; green
This option correctly identifies the color changes for both silver (black due to silver sulfide) and copper (green due to basic copper carbonate) upon oxidation.
A) grey; green
Silver does not typically turn grey upon oxidation; it turns black. Copper does turn green, but the first part is incorrect.
C) black; blue
While silver turns black, copper does not turn blue upon atmospheric oxidation. Copper compounds can be blue (e.g., copper sulfate solution), but the solid oxidation product on exposure to air is green.
D) grey; blue
Both parts of this option are incorrect. Silver turns black, not grey, and copper turns green, not blue, upon atmospheric oxidation.
To find the median of a given set of data, we first need to arrange the data in ascending or descending order. Then, we determine if the number of data points (n) is odd or even. If 'n' is odd, the median is the middle value. If 'n' is even, the median is the average of the two middle values.
C) 100 is the median of the given data set.
This problem can be solved using the concept of work and time, specifically the "Man-Days-Hours-Work" formula. The formula states that the product of the number of men, days, and hours worked per day is directly proportional to the amount of work done. We can set up a ratio between two scenarios to find the unknown quantity.
Understand the formula: The general formula for work problems involving men, days, hours, and work is:
\[ \frac{M_1 D_1 H_1}{W_1} = \frac{M_2 D_2 H_2}{W_2} \]Where:
Identify the given values for the first scenario:
Identify the given values and unknown for the second scenario:
Substitute the values into the formula:
\[ \frac{17 \times 18 \times 8}{26} = \frac{M_2 \times 6 \times 9}{39} \]Simplify and solve for \(M_2\):
First, simplify the fractions on both sides:
\[ \frac{17 \times 18 \times 8}{26} = \frac{M_2 \times 54}{39} \]Cross-multiply or isolate \(M_2\):
\[ M_2 = \frac{17 \times 18 \times 8 \times 39}{26 \times 6 \times 9} \]Now, perform the cancellations:
Let's rewrite the expression for \(M_2\):
\[ M_2 = \frac{17 \times (18) \times 8 \times (39)}{(26) \times 6 \times 9} \]Divide \(18\) by \(6 \times 9 = 54\):
\[ M_2 = \frac{17 \times 1 \times 8 \times 39}{26 \times 3} \]Divide \(39\) by \(3\):
\[ M_2 = \frac{17 \times 1 \times 8 \times 13}{26} \]Divide \(26\) by \(13\):
\[ M_2 = \frac{17 \times 1 \times 8 \times 1}{2} \]Divide \(8\) by \(2\):
\[ M_2 = 17 \times 4 \]Calculate the final value:
\[ M_2 = 68 \text{ men} \]Calculate the number of additional men required:
The question asks for "how many more men should be engaged".
\[ \text{Additional men} = M_2 - M_1 = 68 - 17 = 51 \text{ men} \]C) 51
Self-pollination is the transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant. For this to occur successfully, the flower must possess both male (stamens) and female (pistil) reproductive organs, and these organs must be mature and functional at the same time.
Correct Option: D) bisexual flowers with both stamens and pistil maturing at the same time
To solve this blood relations problem, we need to establish the relationships between the individuals step-by-step based on the given information. We will construct a family tree or a set of relationships to determine how P is related to T.
Therefore, P is T's maternal aunt (mother's sister).
Correct Option: A) Mother's sister
The problem presents a series of terms, each consisting of three letters and a number. We need to identify the pattern in both the letters and the numbers to find the missing term.
So, the letters for the next term are EZX.
The differences are 5, 10, 20, 40. This is a geometric progression where each difference is multiplied by 2 to get the next difference (\(5 \times 2 = 10\), \(10 \times 2 = 20\), \(20 \times 2 = 40\)).
Following this, the next difference should be \(40 \times 2 = 80\).
So, the next number in the series will be \(95 + 80 = 175\).
A) EZX 175 is the correct term as it follows both the letter and number patterns identified.
A man sold an article for ₹346 by first giving a d% discount on its marked price, and then another discount having the same nominal value (in ₹). If the marked price of the article is ₹1,730, then what is the value of d?
The problem involves calculating a discount percentage given the marked price, the final selling price, and information about two successive discounts. The first discount is a percentage 'd%', and the second is a fixed amount equal to 'd' rupees. We will set up an equation based on these discounts and solve for 'd'.
The price after the first discount of d% on the Marked Price is:
\[ \text{Price after 1st discount} = \text{MP} - \left( \frac{d}{100} \times \text{MP} \right) \]\[ = 1730 - \left( \frac{d}{100} \times 1730 \right) \]\[ = 1730 - 17.3d \]The second discount is ₹d. So, the Selling Price (SP) is the price after the first discount minus ₹d:
\[ \text{SP} = (1730 - 17.3d) - d \]\[ 346 = 1730 - 17.3d - d \]\[ 346 = 1730 - 18.3d \]Rearrange the equation to isolate 'd':
\[ 18.3d = 1730 - 346 \]\[ 18.3d = 1384 \]\[ d = \frac{1384}{18.3} \]\[ d = \frac{13840}{183} \]Dividing 13840 by 183:
\[ 13840 \div 183 = 40 \]C) 40 — The calculated value of 'd' is 40.
The question asks for the location where the annual Taj Mahotsav festival is held. This is a factual question related to cultural events and their venues in India, specifically concerning a prominent festival associated with the Taj Mahal.
A) Near the Eastern gate of Taj Mahal — The Taj Mahotsav is indeed held at Shilpgram, which is situated close to the Eastern Gate of the Taj Mahal, making this the correct venue.
The question asks about the religious sect Chaitanya Mahaprabhu was associated with. This requires knowledge of prominent historical religious figures and their affiliations within Indian religious traditions.
Correct Option: B) Chaitanya Mahaprabhu was a prominent saint and social reformer who founded the Gaudiya Vaishnavism tradition. His teachings were centered on the devotion to Krishna, an avatar of Vishnu. Therefore, he was related to the Vaishnava religious sect.
The problem presents two sets of word triads (LIFE - IFEL - FELI and CALM - ALMC - LMCA) and asks to identify the option that follows the same pattern of transformation. We need to analyze the transformation rules from the first word to the second, and from the second to the third, in the given examples.
A) MUGS - UGSM - GSMU
Therefore, option A follows the same relationship.