A2 Level Free Diagnostic

Floating Point Representation

1Which statement best describes Mantissa and exponent?

AA normalised representation uses the available mantissa bits efficiently and gives a unique preferred form for a non-zero value.BMore exponent bits increase range; more mantissa bits increase precision. A fixed word length forces a trade-off between them.CDiscarded low-order bits create representation error; rounding usually reduces maximum error compared with simple truncation.DThe mantissa stores significant binary digits and the exponent scales the binary point using a power of two.

User Defined Data Types and Binary Files

2Which statement best describes Records?

AA record groups related fields that may have different data types into one structured value.BA pointer stores a memory address or reference used to connect dynamically organised records and structures.CSerial files follow order of arrival; sequential files follow a chosen key order and are normally processed in sequence.DFixed-length records allow direct calculation of a record position so one item can be read or updated without scanning earlier records.

Communication

3Which statement best describes Circuit switching?

ALayers divide communication into services with defined interfaces, allowing technologies at one layer to change without redesigning the entire system.BA dedicated end-to-end path is established for the duration of a session, giving predictable capacity but reserving resources even when idle.CData is split into addressed packets sharing network links, improving utilisation but allowing variable delay, loss and reordering.DProtocols such as HTTP, TLS, SMTP and DNS cooperate at different layers to deliver secure network services.

Hardware and Boolean Algebra

4Which statement best describes Boolean identities?

ARISC favours a smaller set of simple instructions and regular execution; CISC provides more complex instructions that can perform multi-step operations.BMultiple cores, processors or pipelines perform work concurrently, but dependencies and communication overhead limit achievable speed-up.CIdentity, null, idempotent, complement, absorption, associative, commutative and distributive laws transform expressions without changing outputs.DThe negation of a conjunction becomes the disjunction of negations, and the negation of a disjunction becomes the conjunction of negations.

Operating System

5Which statement best describes Security and isolation?

AProcesses move between ready, running and blocked states; scheduling algorithms select work according to priorities, fairness and response goals.BPaging divides virtual and physical memory into fixed-size units, allowing non-contiguous allocation and controlled use of secondary storage.CAn interrupt signals an event, causing processor state to be saved before an interrupt service routine handles it and execution resumes.DUser modes, access rights, authentication and process isolation restrict damage from faults or unauthorised actions.

Compiler

6Which statement best describes Lexical analysis?

ATokens are checked against grammar rules and organised into a parse tree or similar structure; grammatical errors are reported.BTypes, declarations, scope and operation compatibility are checked so grammatically valid but meaningless constructs are rejected.CIntermediate or target instructions are produced, with safe transformations improving speed or size without changing intended behaviour.DCharacters are grouped into tokens such as identifiers, keywords, literals and operators; whitespace and comments are handled and symbol-table entries begin.

Declarative Programming

7Which statement best describes Rules?

AA rule derives a conclusion when its stated conditions can be satisfied by facts or other rules.BA goal asks whether a relationship can be proven and may return variable bindings that satisfy the query.CUnification matches terms and assigns variables consistently so a fact or rule can contribute to a proof.DWhen one path fails, the inference engine returns to an earlier choice and tries another matching fact or rule.

Assembly Language

8Which statement best describes Arithmetic and data movement?

AAn opcode identifies the operation and operands identify registers, values or memory locations involved.BLOAD, STORE, MOVE, ADD and SUBTRACT instructions transfer and transform values using registers and memory.CCompare and branch instructions implement selection and loops by changing the program counter when conditions hold.DA trace records the program counter, accumulator or registers, flags and changed memory after each instruction.

Artificial Intelligence

9Which statement best describes Overfitting and generalisation?

AData is collected and prepared, a model is trained, performance is validated on unseen data and the deployed system is monitored.BSupervised learning uses labelled examples to predict targets; unsupervised learning identifies structure without supplied target labels.CAn overfitted model memorises training details and performs poorly on new data; validation and appropriate complexity improve generalisation.DBias, privacy, explainability, security, human oversight and the cost of errors must be evaluated for the deployment context.

Security and Virtual Machine

10Which statement best describes Virtual-machine isolation?

ASymmetric encryption uses a shared secret efficiently; asymmetric encryption uses a public/private key pair for key exchange, signatures and identity mechanisms.BA signature created with a private key and verified with the public key provides evidence of origin and integrity, not confidentiality by itself.CA certificate binds an identity to a public key through a trusted certificate authority and includes validity and issuer information.DA hypervisor separates guest environments and controls access to physical resources, limiting—but not eliminating—the spread of faults or attacks.