Question Bank

20 questions. One correct answer each. Answers in solution-bank.md.

Q1. Which of the following is a valid channel value for QiskitRuntimeService.save_account() in current qiskit-ibm-runtime?

• A) "ibm_q"
• B) "ibm_quantum_platform"
• C) "ibm_quantum_experience"
• D) "aer"

Q2. You are running VQE: each Estimator job's parameters depend on the classical optimizer's processing of the previous job's result. Which execution mode is recommended?

• A) Job mode, submitting each iteration separately
• B) Batch mode, so iterations are parallelized
• C) Session mode
• D) Local testing mode, since VQE cannot run on hardware

Q3. You have 40 independent circuits, all fully specified up front, and you want to compare error-mitigation settings across them as cheaply as possible. Recommended mode?

• A) Session mode, for exclusive access
• B) Job mode, one job per circuit
• C) A session per circuit
• D) Batch mode

Q4. According to IBM's guidance, which mode should you always use to submit a single primitive request?

• A) Job mode
• B) Batch mode, since the overhead is zero
• C) Session mode, since it guarantees earliest start
• D) Any mode — queue time for a single job is lower in sessions

Q5. What execution mode does this code use?

backend = service.least_busy(operational=True, simulator=False)
sampler = SamplerV2(mode=backend)
job = sampler.run([isa_pub])

• A) Session mode, created implicitly
• B) Batch mode
• C) Job mode
• D) Local testing mode

Q6. What happens when the with Session(backend=backend) as session: block exits?

• A) The session stays open until the interactive timeout closes it
• B) The session is canceled and all queued jobs are terminated immediately
• C) Nothing — you must call session.close() explicitly
• D) The session is closed: it stops accepting new jobs, but jobs already submitted run to completion

Q7. Which call returns the real, operational QPU with the fewest pending jobs?

• A) service.backend(least_busy=True)
• B) service.least_busy(operational=True, simulator=False)
• C) service.backends(sort="queue")[0]
• D) QiskitRuntimeService.least_busy(hardware=True)

Q8. You submit a circuit containing an h gate directly to EstimatorV2(mode=backend) where backend is an IBM QPU whose basis gates are rz, sx, x, ecr. What happens?

• A) The primitive transpiles the circuit automatically before running
• B) The job is rejected with an error because the circuit is not an ISA circuit
• C) The h gate is skipped and the rest of the circuit runs
• D) The job runs but results carry a warning flag

Q9. Which tuple is a valid Estimator PUB with parameter values?

• A) (observables, circuit, parameter_values)
• B) (circuit, parameter_values, observables)
• C) (circuit, observables, parameter_values)
• D) (parameter_values, observables, circuit)

Q10. An Estimator PUB has observables of shape (2, 1) and 5 parameter value sets (shape (5,)). What is the shape of result[0].data.evs?

• A) (2, 5)
• B) (5, 2)
• C) (7,)
• D) Broadcasting fails — shapes must match exactly

Q11. Which statement about job = sampler.run(pubs) is TRUE?

• A) run() blocks until all PUBs complete, then returns results
• B) run() returns a job object immediately; job.result() blocks until done
• C) run() returns results directly for local primitives, a job for hardware
• D) run() requires exactly one PUB per call

Q12. In an active session, no new job is submitted within the interactive TTL after the last job completes. What happens?

• A) The session is permanently closed and cannot be used again
• B) The session's max TTL timer pauses until the next job arrives
• C) The session is temporarily deactivated; a later job can reactivate it via the normal queue if max TTL has not been reached
• D) All primitives bound to the session raise an exception

Q13. A session reaches its maximum TTL (max_time) while several of its jobs are still waiting in its queue. What happens to those queued jobs?

• A) They fail
• B) They run to completion because they were accepted before the deadline
• C) They are moved into a new automatically created session
• D) They fall back to job mode in the regular queue

Q14. Which statement about batch mode is TRUE?

• A) Batch jobs are guaranteed to execute in submission order
• B) A batch gives you exclusive access to the QPU between its jobs
• C) Batch jobs are independent and share no state; they may run out of order
• D) Later jobs in a batch can read the results of earlier jobs on the server

Q15. Which limitation applies to Open Plan users?

• A) They cannot submit batch jobs
• B) They cannot submit session jobs
• C) They cannot use least_busy()
• D) They cannot run jobs with more than 100 shots

Q16. You want to check your algorithm's ideal (noise-free) output locally without an IBM account. Which is the most direct choice?

• A) SamplerV2(mode="ibm_brisbane")
• B) StatevectorSampler from qiskit.primitives
• C) Session(backend=FakeManilaV2()) with SamplerV2
• D) service.least_busy(simulator=True)

Q17. What do the fake backends in qiskit_ibm_runtime.fake_provider provide?

• A) Live connections to retired IBM devices
• B) Ideal, noise-free statevector simulation only
• C) QPU snapshots including coupling map, basis gates, and a noise model applied automatically during simulation
• D) A remote cloud simulator that requires saved credentials

Q18. What does this code print or raise?

from qiskit import QuantumCircuit
from qiskit_ibm_runtime import SamplerV2
from qiskit_ibm_runtime.fake_provider import FakeManilaV2
 
qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
qc.measure_all()
 
job = SamplerV2(mode=FakeManilaV2()).run([qc])
print(job.result()[0].data.meas.get_counts())

• A) Noisy Bell-state counts near 50/50 00/11
• B) Exact 50/50 counts, since fake backends are ideal
• C) An error: the circuit is not an ISA circuit for the fake backend's target
• D) An error: fake backends do not support SamplerV2

Q19. Which snippet correctly runs an estimator inside a session?

• A)

with Session(backend=backend) as session:
    estimator = EstimatorV2(mode=session)
    job = estimator.run(pubs)

• B)

with Session(backend) as session:
    estimator = EstimatorV2(session=True)
    job = estimator.run(pubs)

• C)

session = Session(mode=backend)
estimator = EstimatorV2(backend=session)
job = estimator.run(pubs)

• D)

with Session(backend=backend):
    estimator = EstimatorV2(mode="session")
    job = estimator.run(pubs)

Q20. Which set of objects can be passed as mode= when instantiating SamplerV2?

• A) Only a Session object
• B) A backend object, a Session, or a Batch
• C) Only the strings "job", "batch", "session"
• D) A QiskitRuntimeService instance or a backend name list