ZF India Technology Center Data Scientist Interview Questions and Answers for Experienced

Identifying data errors involves systematic checks for inconsistencies, missing values, and outliers in datasets.

• Check for missing values: Use functions like isnull() in Python to identify gaps in data.

• Identify duplicates: Use methods like drop_duplicates() to find and remove repeated entries.

• Validate data types: Ensure that numerical fields contain only numbers, e.g., using pd.to_numeric() in pandas.

• Look for outliers:...read more

Decrease in pH can occur due to various factors in conversion coating.

• Decrease in pH can be caused by the addition of an acid or acidic solution.

• Presence of reactive metals in the coating can lead to a decrease in pH.

• Contamination by organic materials or impurities can also lower the pH.

• Chemical reactions during the conversion coating process may result in pH decrease.

• Examples of conversion coatings include phosphating

To prepare 0.1 N H2SO4 & NaOH, calculate the required amount of solute and dissolve it in distilled water.

• Calculate the molar mass of H2SO4 and NaOH

• Determine the required amount of solute using the formula: N = (W/M) x (1000/V)

• Dissolve the calculated amount of solute in distilled water to make 1 liter of solution

• Standardize the solution using a primary standard

• Use a burette to measure the volume of solution needed for

To cross verify 0.1 normality H2SO4, use a standard solution of NaOH and an indicator.

• Prepare a standard solution of NaOH of known concentration.

• Add a few drops of an indicator such as phenolphthalein to the H2SO4 solution.

• Titrate the H2SO4 solution with the NaOH solution until the endpoint is reached.

• The endpoint is when the indicator changes color, indicating that all the H2SO4 has reacted with the NaOH.

• Calculate the...read more

Prepare a pH buffer solution as per defined standard in tablet.

• Determine the required pH value and buffer capacity

• Select the appropriate buffer system and calculate the required amounts of buffer components

• Dissolve the buffer components in water and adjust the pH as necessary

• Check the pH and adjust if necessary

• Filter the solution and store in a clean container

• Use a calibrated pH meter to verify the pH of the solution

A relay holding circuit diagram is used to keep the relay in the energized state even after the control signal is removed.

• The circuit typically includes a holding contact that maintains the relay coil energized.

• A latching relay can also be used for holding without continuous power supply.

• Examples: ladder logic diagram with a holding contact, latching relay circuit diagram.

PNP and NPN are types of bipolar junction transistors commonly used in electronic circuits.

• PNP transistor has a layer of N-type semiconductor between two layers of P-type semiconductor, while NPN transistor has a layer of P-type semiconductor between two layers of N-type semiconductor.

• In a PNP transistor, current flows from the emitter to the base and then to the collector, while in an NPN transistor, current flows fro...read more

There are various types of sensors used for different purposes.

• Temperature sensors (e.g. thermocouples, thermistors)

• Pressure sensors (e.g. piezoelectric sensors)

• Motion sensors (e.g. accelerometers, gyroscopes)

• Proximity sensors (e.g. ultrasonic sensors)

• Light sensors (e.g. photodiodes, phototransistors)

PLC stands for Programmable Logic Controller, which is a digital computer used for automation of electromechanical processes.

• PLC is used to control machinery in manufacturing processes, such as assembly lines, robotic devices, or any activity that requires high reliability control.

• It is programmed using a specialized computer language, typically ladder logic or function block diagram.

• PLCs are commonly used in industrie...read more